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#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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