Added a check for GL_ARB_explicit_attrib_location extension.

It is enabled by default for OpenGL 3.3, but we need it for some of our shaders in render_geometry.cpp (which are OpenGL >= 3.2) and also for InstancedColorizeShader.

src/graphics/central_settings.cpp

@@ -46,6 +46,7 @@ void CentralVideoSettings::init()
     hasMultiDrawIndirect = false;
     hasTextureCompression = false;
     hasUBO = false;
+    hasExplicitAttribLocation = false;
     hasGS = false;
 
     m_GI_has_artifact = false;
@@ -154,6 +155,11 @@ void CentralVideoSettings::init()
             hasUBO = true;
             Log::info("GLDriver", "ARB Uniform Buffer Object Present");
         }
+        if (!GraphicsRestrictions::isDisabled(GraphicsRestrictions::GR_EXPLICIT_ATTRIB_LOCATION) &&
+            hasGLExtension("GL_ARB_explicit_attrib_location")) {
+            hasExplicitAttribLocation = true;
+            Log::info("GLDriver", "ARB Explicit Attrib Location Present");
+        }
         if (!GraphicsRestrictions::isDisabled(GraphicsRestrictions::GR_GEOMETRY_SHADER) &&
             (m_gl_major_version > 3 || (m_gl_major_version == 3 && m_gl_minor_version >= 2))) {
             hasGS = true;
@@ -229,7 +235,7 @@ bool CentralVideoSettings::needsSRGBCapableVisualWorkaround() const
     return m_need_srgb_visual_workaround;
 }
 
-bool CentralVideoSettings::isARBGeometryShader4Usable() const
+bool CentralVideoSettings::isARBGeometryShadersUsable() const
 {
     return hasGS;
 }
@@ -239,6 +245,11 @@ bool CentralVideoSettings::isARBUniformBufferObjectUsable() const
     return hasUBO;
 }
 
+bool CentralVideoSettings::isARBExplicitAttribLocationUsable() const
+{
+    return hasExplicitAttribLocation;
+}
+
 bool CentralVideoSettings::isEXTTextureCompressionS3TCUsable() const
 {
     return hasTextureCompression;
@@ -311,12 +322,12 @@ bool CentralVideoSettings::isARBMultiDrawIndirectUsable() const
 
 bool CentralVideoSettings::supportsShadows() const
 {
-    return isARBGeometryShader4Usable() && isARBUniformBufferObjectUsable();
+    return isARBGeometryShadersUsable() && isARBUniformBufferObjectUsable() && isARBExplicitAttribLocationUsable();
 }
 
 bool CentralVideoSettings::supportsGlobalIllumination() const
 {
-    return isARBGeometryShader4Usable() && isARBUniformBufferObjectUsable() && !m_GI_has_artifact;
+    return isARBGeometryShadersUsable() && isARBUniformBufferObjectUsable() && isARBExplicitAttribLocationUsable() && !m_GI_has_artifact;
 }
 
 bool CentralVideoSettings::supportsIndirectInstancingRendering() const

src/graphics/central_settings.hpp

@@ -35,6 +35,7 @@ private:
     bool hasTextureView;
     bool hasBindlessTexture;
     bool hasUBO;
+    bool hasExplicitAttribLocation;
     bool hasGS;
     bool hasTextureCompression;
     bool hasAtomics;
@@ -60,7 +61,7 @@ public:
     bool isARBUniformBufferObjectUsable() const;
     bool isEXTTextureCompressionS3TCUsable() const;
     bool isARBTextureViewUsable() const;
-    bool isARBGeometryShader4Usable() const;
+    bool isARBGeometryShadersUsable() const;
     bool isARBTextureStorageUsable() const;
     bool isAMDVertexShaderLayerUsable() const;
     bool isARBComputeShaderUsable() const;
@@ -73,6 +74,7 @@ public:
     bool isARBShaderStorageBufferObjectUsable() const;
     bool isARBImageLoadStoreUsable() const;
     bool isARBMultiDrawIndirectUsable() const;
+    bool isARBExplicitAttribLocationUsable() const;
 
 
     // Are all required extensions available for feature support

src/graphics/graphics_restrictions.cpp

@@ -56,6 +56,7 @@ namespace GraphicsRestrictions
             "BindlessTexture",
             "TextureCompressionS3TC",
             "AMDVertexShaderLayer",
+            "ExplicitAttribLocation",
             "DriverRecentEnough",
             "HighDefinitionTextures",
             "AdvancedPipeline",

src/graphics/graphics_restrictions.hpp

@@ -50,6 +50,7 @@ namespace GraphicsRestrictions
         GR_BINDLESS_TEXTURE,
         GR_EXT_TEXTURE_COMPRESSION_S3TC,
         GR_AMD_VERTEX_SHADER_LAYER,
+        GR_EXPLICIT_ATTRIB_LOCATION,
         GR_DRIVER_RECENT_ENOUGH,
         GR_HIGHDEFINITION_TEXTURES,
         GR_ADVANCED_PIPELINE,

src/graphics/render.cpp

@@ -674,7 +674,7 @@ void IrrDriver::renderGlow(std::vector<GlowData>& glows)
             node->render();
     }
 
-    if (CVS->supportsIndirectInstancingRendering())
+    if (CVS->supportsIndirectInstancingRendering() && CVS->isARBExplicitAttribLocationUsable())
     {
         glBindBuffer(GL_DRAW_INDIRECT_BUFFER, GlowPassCmd::getInstance()->drawindirectcmd);
         InstancedColorizeShader::getInstance()->use();

src/graphics/shader.cpp

@@ -83,6 +83,9 @@ GLuint ShaderBase::loadShader(const std::string &file, unsigned type)
     
     if (CVS->isAMDVertexShaderLayerUsable())
         code << "#extension GL_AMD_vertex_shader_layer : enable\n";
+        
+    if (CVS->isARBExplicitAttribLocationUsable())
+        code << "#extension GL_ARB_explicit_attrib_location : enable\n";
     
     if (CVS->isAZDOEnabled())
     {