OPENGL: Add assertions to check for valid attribute state.

1 files changed, 12 insertions, 0 deletions

diff --git a/backends/graphics/opengl/pipelines/shader.cpp b/backends/graphics/opengl/pipelines/shader.cpp
index 84c42e30ed..8e38458f73 100644
--- a/backends/graphics/opengl/pipelines/shader.cpp
+++ b/backends/graphics/opengl/pipelines/shader.cpp
@@ -32,6 +32,18 @@ ShaderPipeline::ShaderPipeline(Shader *shader)
 	_vertexAttribLocation = shader->getAttributeLocation("position");
 	_texCoordAttribLocation = shader->getAttributeLocation("texCoordIn");
 	_colorAttribLocation = shader->getAttributeLocation("blendColorIn");
+
+	assert(_vertexAttribLocation   != -1);
+	assert(_texCoordAttribLocation != -1);
+	assert(_colorAttribLocation    != -1);
+
+	// One of the attributes needs to be passed through location 0, otherwise
+	// we get no output for GL contexts due to GL compatibility reasons. Let's
+	// check whether this ever happens. If this ever gets hit, we need to
+	// enable location 0 and pass some dummy values through it to fix output.
+	assert(   _vertexAttribLocation == 0
+	       || _texCoordAttribLocation == 0
+	       || _colorAttribLocation == 0);
 }
 
 void ShaderPipeline::activateInternal() {