From f6da3ba9be27ff9b279730603c517c4cb5e57007 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Konstantin=20K=C3=A4fer?= <mail@kkaefer.com>
Date: Thu, 3 May 2018 21:48:58 +0200
Subject: iOS: Add custom layer example to debugging app (#7734)

---
 platform/darwin/app/LimeGreenStyleLayer.m | 58 +++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 platform/darwin/app/LimeGreenStyleLayer.m

(limited to 'platform/darwin/app/LimeGreenStyleLayer.m')

diff --git a/platform/darwin/app/LimeGreenStyleLayer.m b/platform/darwin/app/LimeGreenStyleLayer.m
new file mode 100644
index 0000000000..98e96381b6
--- /dev/null
+++ b/platform/darwin/app/LimeGreenStyleLayer.m
@@ -0,0 +1,58 @@
+#import "LimeGreenStyleLayer.h"
+@import GLKit;
+
+@implementation LimeGreenStyleLayer {
+    GLuint _program;
+    GLuint _vertexShader;
+    GLuint _fragmentShader;
+    GLuint _buffer;
+    GLuint _aPos;
+}
+
+- (void)didMoveToMapView:(MGLMapView *)mapView {
+    static const GLchar *vertexShaderSource = "attribute vec2 a_pos; void main() { gl_Position = vec4(a_pos, 1, 1); }";
+    static const GLchar *fragmentShaderSource = "void main() { gl_FragColor = vec4(0, 0.5, 0, 0.5); }";
+
+    _program = glCreateProgram();
+    _vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    _fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+
+    glShaderSource(_vertexShader, 1, &vertexShaderSource, NULL);
+    glCompileShader(_vertexShader);
+    glAttachShader(_program, _vertexShader);
+    glShaderSource(_fragmentShader, 1, &fragmentShaderSource, NULL);
+    glCompileShader(_fragmentShader);
+    glAttachShader(_program, _fragmentShader);
+    glLinkProgram(_program);
+    _aPos = glGetAttribLocation(_program, "a_pos");
+
+    GLfloat triangle[] = { 0, 0.5, 0.5, -0.5, -0.5, -0.5 };
+    glGenBuffers(1, &_buffer);
+    glBindBuffer(GL_ARRAY_BUFFER, _buffer);
+    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(GLfloat), triangle, GL_STATIC_DRAW);
+}
+
+- (void)drawInMapView:(MGLMapView *)mapView withContext:(MGLStyleLayerDrawingContext)context {
+    glUseProgram(_program);
+    glBindBuffer(GL_ARRAY_BUFFER, _buffer);
+    glEnableVertexAttribArray(_aPos);
+    glVertexAttribPointer(_aPos, 2, GL_FLOAT, GL_FALSE, 0, NULL);
+    glDisable(GL_STENCIL_TEST);
+    glDisable(GL_DEPTH_TEST);
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 3);
+}
+
+- (void)willMoveFromMapView:(MGLMapView *)mapView {
+    if (!_program) {
+        return;
+    }
+
+    glDeleteBuffers(1, &_buffer);
+    glDetachShader(_program, _vertexShader);
+    glDetachShader(_program, _fragmentShader);
+    glDeleteShader(_vertexShader);
+    glDeleteShader(_fragmentShader);
+    glDeleteProgram(_program);
+}
+
+@end
-- 
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