[core] De-duplicate shader prelude source

18 files changed, 141 insertions, 929 deletions

diff --git a/cmake/core-files.cmake b/cmake/core-files.cmake
index a9fe077db9..b5baff264c 100644
--- a/cmake/core-files.cmake
+++ b/cmake/core-files.cmake
@@ -205,6 +205,8 @@ set(MBGL_CORE_FILES
     src/mbgl/shaders/line_pattern.hpp
     src/mbgl/shaders/line_sdf.cpp
     src/mbgl/shaders/line_sdf.hpp
+    src/mbgl/shaders/preludes.cpp
+    src/mbgl/shaders/preludes.hpp
     src/mbgl/shaders/raster.cpp
     src/mbgl/shaders/raster.hpp
     src/mbgl/shaders/symbol_icon.cpp
diff --git a/scripts/generate-shaders.js b/scripts/generate-shaders.js
index 2949ebd007..892620cf21 100755
--- a/scripts/generate-shaders.js
+++ b/scripts/generate-shaders.js
@@ -8,6 +8,41 @@ const outputPath = 'src/mbgl/shaders';
 
 require('./style-code');
 
+const vertexPrelude = fs.readFileSync(path.join(inputPath, '_prelude.vertex.glsl'));
+const fragmentPrelude = fs.readFileSync(path.join(inputPath, '_prelude.fragment.glsl'));
+
+writeIfModified(path.join(outputPath, 'preludes.hpp'), `// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+
+#pragma once
+
+namespace mbgl {
+namespace shaders {
+
+extern const char* vertexPrelude;
+extern const char* fragmentPrelude;
+
+} // namespace shaders
+} // namespace mbgl
+`);
+
+writeIfModified(path.join(outputPath, 'preludes.cpp'), `// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+
+#include <mbgl/shaders/preludes.hpp>
+
+namespace mbgl {
+namespace shaders {
+
+const char* vertexPrelude = R"MBGL_SHADER(
+${vertexPrelude}
+)MBGL_SHADER";
+const char* fragmentPrelude = R"MBGL_SHADER(
+${fragmentPrelude}
+)MBGL_SHADER";
+
+} // namespace shaders
+} // namespace mbgl
+`);
+
 [
     'circle',
     'collision_box',
@@ -34,9 +69,8 @@ require('./style-code');
     }
 
     function vertexSource() {
-        const prelude = fs.readFileSync(path.join(inputPath, '_prelude.vertex.glsl'));
         const source = fs.readFileSync(path.join(inputPath, shaderName + '.vertex.glsl'), 'utf8');
-        return prelude + applyPragmas(source, {
+        return applyPragmas(source, {
                 define: [
                     "uniform lowp float a_{name}_t;",
                     "attribute {precision} {type} a_{name}_min;",
@@ -50,9 +84,8 @@ require('./style-code');
     }
 
     function fragmentSource() {
-        const prelude = fs.readFileSync(path.join(inputPath, '_prelude.fragment.glsl'));
         const source = fs.readFileSync(path.join(inputPath, shaderName + '.fragment.glsl'), 'utf8');
-        return prelude + applyPragmas(source, {
+        return applyPragmas(source, {
                 define: [
                     "varying {precision} {type} {name};"
                 ],
diff --git a/src/mbgl/programs/program.hpp b/src/mbgl/programs/program.hpp
index e75dbebf18..ffad767c3a 100644
--- a/src/mbgl/programs/program.hpp
+++ b/src/mbgl/programs/program.hpp
@@ -4,6 +4,7 @@
 #include <mbgl/programs/program_parameters.hpp>
 #include <mbgl/programs/attributes.hpp>
 #include <mbgl/style/paint_property.hpp>
+#include <mbgl/shaders/preludes.hpp>
 
 #include <sstream>
 #include <cassert>
@@ -45,7 +46,7 @@ public:
     }
 
     static std::string fragmentSource(const ProgramParameters& parameters) {
-        std::string source = pixelRatioDefine(parameters) + Shaders::fragmentSource;
+        std::string source = pixelRatioDefine(parameters) + shaders::fragmentPrelude + Shaders::fragmentSource;
         if (parameters.overdraw) {
             assert(source.find("#ifdef OVERDRAW_INSPECTOR") != std::string::npos);
             source.replace(source.find_first_of('\n'), 1, "\n#define OVERDRAW_INSPECTOR\n");
@@ -54,7 +55,7 @@ public:
     }
 
     static std::string vertexSource(const ProgramParameters& parameters) {
-        return pixelRatioDefine(parameters) + Shaders::vertexSource;
+        return pixelRatioDefine(parameters) + shaders::vertexPrelude + Shaders::vertexSource;
     }
 
     template <class DrawMode>
diff --git a/src/mbgl/shaders/circle.cpp b/src/mbgl/shaders/circle.cpp
index 592a883fb3..4b2bb7cecf 100644
--- a/src/mbgl/shaders/circle.cpp
+++ b/src/mbgl/shaders/circle.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* circle::name = "circle";
 const char* circle::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 uniform mat4 u_matrix;
 uniform bool u_scale_with_map;
 uniform vec2 u_extrude_scale;
@@ -130,23 +76,6 @@ void main(void) {
 
 )MBGL_SHADER";
 const char* circle::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 varying lowp vec4 color;
 varying mediump float radius;
 varying lowp float blur;
diff --git a/src/mbgl/shaders/collision_box.cpp b/src/mbgl/shaders/collision_box.cpp
index 6f2b9f3824..5f733c6a1e 100644
--- a/src/mbgl/shaders/collision_box.cpp
+++ b/src/mbgl/shaders/collision_box.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* collision_box::name = "collision_box";
 const char* collision_box::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 attribute vec2 a_pos;
 attribute vec2 a_extrude;
 attribute vec2 a_data;
@@ -80,23 +26,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* collision_box::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform float u_zoom;
 uniform float u_maxzoom;
 
diff --git a/src/mbgl/shaders/debug.cpp b/src/mbgl/shaders/debug.cpp
index 2659b2ca79..27a15698d4 100644
--- a/src/mbgl/shaders/debug.cpp
+++ b/src/mbgl/shaders/debug.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* debug::name = "debug";
 const char* debug::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 attribute vec2 a_pos;
 
 uniform mat4 u_matrix;
@@ -71,23 +17,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* debug::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform lowp vec4 u_color;
 
 void main() {
diff --git a/src/mbgl/shaders/fill.cpp b/src/mbgl/shaders/fill.cpp
index 066adee447..d0fc3a7033 100644
--- a/src/mbgl/shaders/fill.cpp
+++ b/src/mbgl/shaders/fill.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* fill::name = "fill";
 const char* fill::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 attribute vec2 a_pos;
 
 uniform mat4 u_matrix;
@@ -83,23 +29,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* fill::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 varying lowp vec4 color;
 varying lowp float opacity;
 
diff --git a/src/mbgl/shaders/fill_outline.cpp b/src/mbgl/shaders/fill_outline.cpp
index 0f0f3806a9..d6f8d63715 100644
--- a/src/mbgl/shaders/fill_outline.cpp
+++ b/src/mbgl/shaders/fill_outline.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* fill_outline::name = "fill_outline";
 const char* fill_outline::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 attribute vec2 a_pos;
 
 uniform mat4 u_matrix;
@@ -87,23 +33,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* fill_outline::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 varying lowp vec4 outline_color;
 varying lowp float opacity;
 
diff --git a/src/mbgl/shaders/fill_outline_pattern.cpp b/src/mbgl/shaders/fill_outline_pattern.cpp
index 3921a83e6b..6e9d6ad9a1 100644
--- a/src/mbgl/shaders/fill_outline_pattern.cpp
+++ b/src/mbgl/shaders/fill_outline_pattern.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* fill_outline_pattern::name = "fill_outline_pattern";
 const char* fill_outline_pattern::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 uniform mat4 u_matrix;
 uniform vec2 u_world;
 uniform vec2 u_pattern_size_a;
@@ -95,23 +41,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* fill_outline_pattern::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform vec2 u_pattern_tl_a;
 uniform vec2 u_pattern_br_a;
 uniform vec2 u_pattern_tl_b;
diff --git a/src/mbgl/shaders/fill_pattern.cpp b/src/mbgl/shaders/fill_pattern.cpp
index 822a0f7b8f..329a292eed 100644
--- a/src/mbgl/shaders/fill_pattern.cpp
+++ b/src/mbgl/shaders/fill_pattern.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* fill_pattern::name = "fill_pattern";
 const char* fill_pattern::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 uniform mat4 u_matrix;
 uniform vec2 u_pattern_size_a;
 uniform vec2 u_pattern_size_b;
@@ -91,23 +37,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* fill_pattern::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform vec2 u_pattern_tl_a;
 uniform vec2 u_pattern_br_a;
 uniform vec2 u_pattern_tl_b;
diff --git a/src/mbgl/shaders/line.cpp b/src/mbgl/shaders/line.cpp
index 59fa9f0cf2..bd3256ad3b 100644
--- a/src/mbgl/shaders/line.cpp
+++ b/src/mbgl/shaders/line.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* line::name = "line";
 const char* line::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 
 
 // the distance over which the line edge fades out.
@@ -164,23 +110,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* line::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 varying lowp vec4 color;
 varying lowp float blur;
 varying lowp float opacity;
diff --git a/src/mbgl/shaders/line_pattern.cpp b/src/mbgl/shaders/line_pattern.cpp
index 7f2a31ee44..2be98deab3 100644
--- a/src/mbgl/shaders/line_pattern.cpp
+++ b/src/mbgl/shaders/line_pattern.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* line_pattern::name = "line_pattern";
 const char* line_pattern::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 // floor(127 / 2) == 63.0
 // the maximum allowed miter limit is 2.0 at the moment. the extrude normal is
 // stored in a byte (-128..127). we scale regular normals up to length 63, but
@@ -163,23 +109,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* line_pattern::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform vec2 u_pattern_size_a;
 uniform vec2 u_pattern_size_b;
 uniform vec2 u_pattern_tl_a;
diff --git a/src/mbgl/shaders/line_sdf.cpp b/src/mbgl/shaders/line_sdf.cpp
index 011c1c3738..5f01cf00c0 100644
--- a/src/mbgl/shaders/line_sdf.cpp
+++ b/src/mbgl/shaders/line_sdf.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* line_sdf::name = "line_sdf";
 const char* line_sdf::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 // floor(127 / 2) == 63.0
 // the maximum allowed miter limit is 2.0 at the moment. the extrude normal is
 // stored in a byte (-128..127). we scale regular normals up to length 63, but
@@ -175,23 +121,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* line_sdf::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 
 uniform sampler2D u_image;
 uniform float u_sdfgamma;
diff --git a/src/mbgl/shaders/preludes.cpp b/src/mbgl/shaders/preludes.cpp
new file mode 100644
index 0000000000..a0e9414ceb
--- /dev/null
+++ b/src/mbgl/shaders/preludes.cpp
@@ -0,0 +1,87 @@
+// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+
+#include <mbgl/shaders/preludes.hpp>
+
+namespace mbgl {
+namespace shaders {
+
+const char* vertexPrelude = R"MBGL_SHADER(
+#ifdef GL_ES
+precision highp float;
+#else
+
+#if !defined(lowp)
+#define lowp
+#endif
+
+#if !defined(mediump)
+#define mediump
+#endif
+
+#if !defined(highp)
+#define highp
+#endif
+
+#endif
+
+float evaluate_zoom_function_1(const vec4 values, const float t) {
+    if (t < 1.0) {
+        return mix(values[0], values[1], t);
+    } else if (t < 2.0) {
+        return mix(values[1], values[2], t - 1.0);
+    } else {
+        return mix(values[2], values[3], t - 2.0);
+    }
+}
+vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
+    if (t < 1.0) {
+        return mix(value0, value1, t);
+    } else if (t < 2.0) {
+        return mix(value1, value2, t - 1.0);
+    } else {
+        return mix(value2, value3, t - 2.0);
+    }
+}
+
+// The offset depends on how many pixels are between the world origin and the edge of the tile:
+// vec2 offset = mod(pixel_coord, size)
+//
+// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
+// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
+//
+// The pixel_coord is passed in as two 16 bit values:
+// pixel_coord_upper = floor(pixel_coord / 2^16)
+// pixel_coord_lower = mod(pixel_coord, 2^16)
+//
+// The offset is calculated in a series of steps that should preserve this precision:
+vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
+    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
+
+    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
+    return (tile_units_to_pixels * pos + offset) / pattern_size;
+}
+
+)MBGL_SHADER";
+const char* fragmentPrelude = R"MBGL_SHADER(
+#ifdef GL_ES
+precision mediump float;
+#else
+
+#if !defined(lowp)
+#define lowp
+#endif
+
+#if !defined(mediump)
+#define mediump
+#endif
+
+#if !defined(highp)
+#define highp
+#endif
+
+#endif
+
+)MBGL_SHADER";
+
+} // namespace shaders
+} // namespace mbgl
diff --git a/src/mbgl/shaders/preludes.hpp b/src/mbgl/shaders/preludes.hpp
new file mode 100644
index 0000000000..a3abc9001f
--- /dev/null
+++ b/src/mbgl/shaders/preludes.hpp
@@ -0,0 +1,12 @@
+// NOTE: DO NOT CHANGE THIS FILE. IT IS AUTOMATICALLY GENERATED.
+
+#pragma once
+
+namespace mbgl {
+namespace shaders {
+
+extern const char* vertexPrelude;
+extern const char* fragmentPrelude;
+
+} // namespace shaders
+} // namespace mbgl
diff --git a/src/mbgl/shaders/raster.cpp b/src/mbgl/shaders/raster.cpp
index ba0aa5cd05..eb7a2db240 100644
--- a/src/mbgl/shaders/raster.cpp
+++ b/src/mbgl/shaders/raster.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* raster::name = "raster";
 const char* raster::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 uniform mat4 u_matrix;
 uniform vec2 u_tl_parent;
 uniform float u_scale_parent;
@@ -80,23 +26,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* raster::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform float u_fade_t;
 uniform float u_opacity;
 uniform sampler2D u_image0;
diff --git a/src/mbgl/shaders/symbol_icon.cpp b/src/mbgl/shaders/symbol_icon.cpp
index e6728e15de..5945f1f3b1 100644
--- a/src/mbgl/shaders/symbol_icon.cpp
+++ b/src/mbgl/shaders/symbol_icon.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* symbol_icon::name = "symbol_icon";
 const char* symbol_icon::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 attribute vec2 a_pos;
 attribute vec2 a_offset;
 attribute vec2 a_texture_pos;
@@ -109,23 +55,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* symbol_icon::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 uniform sampler2D u_texture;
 uniform sampler2D u_fadetexture;
 
diff --git a/src/mbgl/shaders/symbol_sdf.cpp b/src/mbgl/shaders/symbol_sdf.cpp
index e087242bf8..ccb4b9cee6 100644
--- a/src/mbgl/shaders/symbol_sdf.cpp
+++ b/src/mbgl/shaders/symbol_sdf.cpp
@@ -7,60 +7,6 @@ namespace shaders {
 
 const char* symbol_sdf::name = "symbol_sdf";
 const char* symbol_sdf::vertexSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision highp float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
-
-float evaluate_zoom_function_1(const vec4 values, const float t) {
-    if (t < 1.0) {
-        return mix(values[0], values[1], t);
-    } else if (t < 2.0) {
-        return mix(values[1], values[2], t - 1.0);
-    } else {
-        return mix(values[2], values[3], t - 2.0);
-    }
-}
-vec4 evaluate_zoom_function_4(const vec4 value0, const vec4 value1, const vec4 value2, const vec4 value3, const float t) {
-    if (t < 1.0) {
-        return mix(value0, value1, t);
-    } else if (t < 2.0) {
-        return mix(value1, value2, t - 1.0);
-    } else {
-        return mix(value2, value3, t - 2.0);
-    }
-}
-
-// The offset depends on how many pixels are between the world origin and the edge of the tile:
-// vec2 offset = mod(pixel_coord, size)
-//
-// At high zoom levels there are a ton of pixels between the world origin and the edge of the tile.
-// The glsl spec only guarantees 16 bits of precision for highp floats. We need more than that.
-//
-// The pixel_coord is passed in as two 16 bit values:
-// pixel_coord_upper = floor(pixel_coord / 2^16)
-// pixel_coord_lower = mod(pixel_coord, 2^16)
-//
-// The offset is calculated in a series of steps that should preserve this precision:
-vec2 get_pattern_pos(const vec2 pixel_coord_upper, const vec2 pixel_coord_lower,
-    const vec2 pattern_size, const float tile_units_to_pixels, const vec2 pos) {
-
-    vec2 offset = mod(mod(mod(pixel_coord_upper, pattern_size) * 256.0, pattern_size) * 256.0 + pixel_coord_lower, pattern_size);
-    return (tile_units_to_pixels * pos + offset) / pattern_size;
-}
 const float PI = 3.141592653589793;
 
 attribute vec2 a_pos;
@@ -172,23 +118,6 @@ void main() {
 
 )MBGL_SHADER";
 const char* symbol_sdf::fragmentSource = R"MBGL_SHADER(
-#ifdef GL_ES
-precision mediump float;
-#else
-
-#if !defined(lowp)
-#define lowp
-#endif
-
-#if !defined(mediump)
-#define mediump
-#endif
-
-#if !defined(highp)
-#define highp
-#endif
-
-#endif
 #define SDF_PX 8.0
 #define EDGE_GAMMA 0.105/DEVICE_PIXEL_RATIO