I am using OpenGL ES 3.2 and the NVIDIA driver 361.00 on a Pixel C tablet with Tegra X1 GPU. I would like to use a compute shader to write data to a colour map and then later I will use some graphics shaders to display the image.
I already have this concept working using desktop GL and now I want to port to mobile. I am implementing the GL in Java rather than in native code. I extend GLSurfaceView and the GLSurfaceView.Renderer and then during the OnSurfaceCreated callback I initialise the shader programs and textures etc.
GLSurfaceView
GLSurfaceView.Renderer
OnSurfaceCreated
The compute shader compiles just fine without any errors:
#version 320 es layout(binding = 0, rgba32f) uniform highp image2D colourMap; layout(local_size_x = 128, local_size_y = 1, local_size_z = 1) in; void main() { imageStore(colourMap, ivec2(gl_GlobalInvocationID.xy), vec4(1.0f, 0.0f, 0.0f, 1.0f)); }
And I initialise a texture
// Generate a 2D texture GLES31.glGenTextures(1, colourMap, 0); GLES31.glBindTexture(GLES31.GL_TEXTURE_2D, colourMap[0]); // Set interpolation to nearest GLES31.glTexParameteri(GLES31.GL_TEXTURE_2D, GLES31.GL_TEXTURE_MAG_FILTER, GLES31.GL_LINEAR); GLES31.glTexParameteri(GLES31.GL_TEXTURE_2D, GLES31.GL_TEXTURE_MIN_FILTER, GLES31.GL_LINEAR); // Create some dummy texture to begin with so we can see if it changes float texData[] = new float[texWidth * texHeight * 4]; for (int j = 0; j < texHeight; j++) { for (int i = 0; i < texWidth; i++) { // Set a few pixels in here... } } Buffer texDataBuffer = FloatBuffer.wrap(texData); GLES31.glTexImage2D(GLES31.GL_TEXTURE_2D, 0, GLES31.GL_RGBA32F, texWidth, texHeight, 0, GLES31.GL_RGBA, GLES31.GL_FLOAT, texDataBuffer);
After this I set the image unit in the shader here:
GLES31.glUseProgram(idComputeShaderProgram); int loc = GLES31.glGetUniformLocation(idComputeShaderProgram, "colourMap"); if (loc == -1) Log.e("Error", "Cannot locate variable"); GLES31.glUniform1i(loc, 0);
After every call to GL I check for errors using GLES31.glGetError() -- left out here for clarity. This final line is the only one which errors. The error code translates to GL_INVALID_OPERATION. As the documentation describes, glUniform1i can return this error under quite a few circumstances. I have checked all these and also believe that none of them apply. The shader compiles correctly and the program object is valid. The location of the variable is also valid. I have even used glGetActiveUniform() to get the type of the variable and it returns a type of 36941 which translates to GL_IMAGE_2D which I believe is an integer.
GLES31.glGetError()
GL_INVALID_OPERATION
glUniform1i
glGetActiveUniform()
GL_IMAGE_2D
I don't know what I can be doing wrong. Am I missing an extension or something? Documentation for GLES in Java for Android is dire.
Yes, thanks Pete. Much appreciated.