refactor vao object to use acutal OpenGL IDs rather than object pointers

src/geometry/vao.cpp

@@ -0,0 +1,46 @@
+#include <mbgl/geometry/vao.hpp>
+
+namespace mbgl {
+
+#if GL_ARB_vertex_array_object
+
+VertexArrayObject::~VertexArrayObject() {
+    if (vao) {
+        glDeleteVertexArrays(1, &vao);
+    }
+}
+
+void VertexArrayObject::bindVertexArrayObject() {
+    if (!vao) {
+        glGenVertexArrays(1, &vao);
+    }
+    glBindVertexArray(vao);
+}
+
+void VertexArrayObject::verifyBinding(Shader &shader, GLuint vertexBuffer, GLuint elementsBuffer,
+                                      char *offset) {
+    if (bound_shader != shader.getID()) {
+        throw std::runtime_error(std::string("trying to rebind VAO to another shader from " +
+                                             std::to_string(bound_shader) + "(" + bound_shader_name + ") to " +
+                                             std::to_string(shader.getID()) + "(" + shader.name + ")" ));
+    } else if (bound_offset != offset) {
+        throw std::runtime_error("trying to bind VAO to another offset");
+    } else if (bound_vertex_buffer != vertexBuffer) {
+        throw std::runtime_error("trying to bind VAO to another vertex buffer");
+    } else if (bound_elements_buffer != elementsBuffer) {
+        throw std::runtime_error("trying to bind VAO to another elements buffer");
+    }
+}
+
+void VertexArrayObject::storeBinding(Shader &shader, GLuint vertexBuffer, GLuint elementsBuffer,
+                                     char *offset) {
+    bound_shader = shader.getID();
+    bound_shader_name = shader.name;
+    bound_offset = offset;
+    bound_vertex_buffer = vertexBuffer;
+    bound_elements_buffer = elementsBuffer;
+}
+
+#endif
+
+}

src/geometry/vertex_buffer.cpp

@@ -26,3 +26,7 @@ void VertexBuffer::bind() {
         glBindBuffer(GL_ARRAY_BUFFER, buffer);
     }
 }
+
+uint32_t VertexBuffer::getID() const {
+    return buffer;
+}

src/shader/composite_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 CompositeShader::CompositeShader()
     : Shader(
+         "composite",
          shaders[COMPOSITE_SHADER].vertex,
          shaders[COMPOSITE_SHADER].fragment
          ) {

src/shader/dot_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 DotShader::DotShader()
 : Shader(
+         "dot",
          shaders[DOT_SHADER].vertex,
          shaders[DOT_SHADER].fragment
          ) {

src/shader/gaussian_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 GaussianShader::GaussianShader()
     : Shader(
+         "gaussian",
          shaders[GAUSSIAN_SHADER].vertex,
          shaders[GAUSSIAN_SHADER].fragment
          ) {

src/shader/icon_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 IconShader::IconShader()
     : Shader(
+         "icon",
          shaders[ICON_SHADER].vertex,
          shaders[ICON_SHADER].fragment
          ) {

src/shader/line_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 LineShader::LineShader()
     : Shader(
+        "line",
         shaders[LINE_SHADER].vertex,
         shaders[LINE_SHADER].fragment
     ) {

src/shader/linejoin_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 LinejoinShader::LinejoinShader()
     : Shader(
+        "linejoin",
         shaders[LINEJOIN_SHADER].vertex,
         shaders[LINEJOIN_SHADER].fragment
     ) {

src/shader/outline_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 OutlineShader::OutlineShader()
     : Shader(
+        "outline",
         shaders[OUTLINE_SHADER].vertex,
         shaders[OUTLINE_SHADER].fragment
     ) {

src/shader/pattern_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 PatternShader::PatternShader()
     : Shader(
+        "pattern",
         shaders[PATTERN_SHADER].vertex,
         shaders[PATTERN_SHADER].fragment
     ) {

src/shader/plain_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 PlainShader::PlainShader()
     : Shader(
+        "plain",
         shaders[PLAIN_SHADER].vertex,
         shaders[PLAIN_SHADER].fragment
     ) {

src/shader/raster_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 RasterShader::RasterShader()
     : Shader(
+         "raster",
          shaders[RASTER_SHADER].vertex,
          shaders[RASTER_SHADER].fragment
          ) {

src/shader/shader.cpp

@@ -8,8 +8,9 @@
 
 using namespace mbgl;
 
-Shader::Shader(const GLchar *vertSource, const GLchar *fragSource)
-    : valid(false),
+Shader::Shader(const char *name, const GLchar *vertSource, const GLchar *fragSource)
+    : name(name),
+      valid(false),
       program(0) {
     util::timer timer("shader compilation", Event::Shader);
 

src/shader/text_shader.cpp

@@ -8,6 +8,7 @@ using namespace mbgl;
 
 TextShader::TextShader()
     : Shader(
+        "text",
         shaders[TEXT_SHADER].vertex,
         shaders[TEXT_SHADER].fragment
     ) {