port mat4.perspective and mat4.rotate_x

2 files changed, 57 insertions, 0 deletions

diff --git a/include/mbgl/util/mat4.hpp b/include/mbgl/util/mat4.hpp
index 4279113d21..e59712ed0d 100644
--- a/include/mbgl/util/mat4.hpp
+++ b/include/mbgl/util/mat4.hpp
@@ -33,8 +33,10 @@ namespace matrix {
 
 void identity(mat4& out);
 void ortho(mat4& out, float left, float right, float bottom, float top, float near, float far);
+void perspective(mat4& out, float fovy, float aspect, float near, float far);
 void copy(mat4& out, const mat4& a);
 void translate(mat4& out, const mat4& a, float x, float y, float z);
+void rotate_x(mat4& out, const mat4& a, float rad);
 void rotate_z(mat4& out, const mat4& a, float rad);
 void scale(mat4& out, const mat4& a, float x, float y, float z);
 void multiply(mat4& out, const mat4& a, const mat4& b);
diff --git a/src/mbgl/util/mat4.cpp b/src/mbgl/util/mat4.cpp
index cabd8e2842..d48558dc22 100644
--- a/src/mbgl/util/mat4.cpp
+++ b/src/mbgl/util/mat4.cpp
@@ -67,6 +67,27 @@ void matrix::ortho(mat4& out, float left, float right, float bottom, float top,
     out[15] = 1.0f;
 }
 
+void matrix::perspective(mat4& out, float fovy, float aspect, float near, float far) {
+    float f = 1.0f / std::tan(fovy / 2.0f),
+          nf = 1.0f / (near - far);
+    out[0] = f / aspect;
+    out[1] = 0.0f;
+    out[2] = 0.0f;
+    out[3] = 0.0f;
+    out[4] = 0.0f;
+    out[5] = f;
+    out[6] = 0.0f;
+    out[7] = 0.0f;
+    out[8] = 0.0f;
+    out[9] = 0.0f;
+    out[10] = (far + near) * nf;
+    out[11] = -1.0f;
+    out[12] = 0.0f;
+    out[13] = 0.0f;
+    out[14] = (2.0f * far * near) * nf;
+    out[15] = 0.0f;
+}
+
 void matrix::copy(mat4& out, const mat4& a) {
     out[0] = a[0];
     out[1] = a[1];
@@ -112,6 +133,40 @@ void matrix::translate(mat4& out, const mat4& a, float x, float y, float z) {
     }
 }
 
+void matrix::rotate_x(mat4& out, const mat4& a, float rad) {
+    float s = std::sin(rad),
+        c = std::cos(rad),
+        a10 = a[4],
+        a11 = a[5],
+        a12 = a[6],
+        a13 = a[7],
+        a20 = a[8],
+        a21 = a[9],
+        a22 = a[10],
+        a23 = a[11];
+
+    if (&a != &out) { // If the source and destination differ, copy the unchanged rows
+        out[0]  = a[0];
+        out[1]  = a[1];
+        out[2]  = a[2];
+        out[3]  = a[3];
+        out[12] = a[12];
+        out[13] = a[13];
+        out[14] = a[14];
+        out[15] = a[15];
+    }
+
+    // Perform axis-specific matrix multiplication
+    out[4] = a10 * c + a20 * s;
+    out[5] = a11 * c + a21 * s;
+    out[6] = a12 * c + a22 * s;
+    out[7] = a13 * c + a23 * s;
+    out[8] = a20 * c - a10 * s;
+    out[9] = a21 * c - a11 * s;
+    out[10] = a22 * c - a12 * s;
+    out[11] = a23 * c - a13 * s;
+}
+
 void matrix::rotate_z(mat4& out, const mat4& a, float rad) {
     float s = std::sin(rad),
           c = std::cos(rad),