Very strange problems with texture in Compute Shader

[Destranix]

Hy,
Here is my code. It’s java, but the glCommands are nearly the same:

        ssbo=glGenBuffers();

	calcPointsShaderProgram.bind();
	int pointscount=width*height;
	glBindBuffer(GL_COPY_WRITE_BUFFER,ssbo);
	glBufferData(GL_COPY_WRITE_BUFFER, FloatBuffer.allocate(pointscount*4), GL_DYNAMIC_DRAW);
	glBindBuffer(GL_COPY_WRITE_BUFFER,0);
		
	glBindBufferBase(GL_SHADER_STORAGE_BUFFER,0,ssbo);
		
	glMemoryBarrier(GL_ALL_BARRIER_BITS);
		
	int tmpTexture=glGenTextures();
	glBindTexture(GL_TEXTURE_2D, tmpTexture);
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, screen_width, screen_height, 0, GL_RGB, GL_FLOAT, (ByteBuffer) null);
	glGenerateMipmap(GL_TEXTURE_2D);
	glBindTexture(GL_TEXTURE_2D,0);
		
	//glCopyImageSubData(feedbackTexture,GL_TEXTURE_2D,0,0,0,0,tmpTexture,GL_TEXTURE_2D,0,0,0,0,screen_width,screen_height,1);//falsch kopiert?
	glBindFramebuffer(GL_READ_FRAMEBUFFER,feedbackFbo);
	glReadBuffer(GL_COLOR_ATTACHMENT0);
	glEnable(GL_TEXTURE_2D);  
        glBindTexture(GL_TEXTURE_2D,tmpTexture);
        glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 0, 0, screen_width,screen_height, 0);
        glBindTexture(GL_TEXTURE_2D,0);
	glBindFramebuffer(GL_READ_FRAMEBUFFER,0);
		
	glActiveTexture(GL_TEXTURE0);
	//glBindTexture(GL_TEXTURE_2D,feedbackTexture);
	glBindTexture(GL_TEXTURE_2D,tmpTexture);
	//glBindImageTexture(0, feedbackTexture, 0, false, 0, GL_READ_ONLY, GL_RGBA32F);

	calcPointsShaderProgram.setUniform("fragCoordMap",0);
		
	glDispatchCompute(1,1,1);
	glMemoryBarrier(GL_ALL_BARRIER_BITS);
		
	glBindBufferBase(GL_SHADER_STORAGE_BUFFER,0,ssbo);
	float[] pointsOutput=new float[pointscount];
	glGetBufferSubData(GL_SHADER_STORAGE_BUFFER,0, pointsOutput);
		
	for(int i=0;i<pointsOutput.length;i+=4){
		if((pointsOutput[i]!=0||pointsOutput[i+1]!=0||pointsOutput[i+2]!=0)&&!(Float.isNaN(pointsOutput[i])||Float.isNaN(pointsOutput[i+1])||Float.isNaN(pointsOutput[i+2]))){
			System.out.println((i+1)+"X: "+pointsOutput[i]+" Y: "+pointsOutput[i+1]+" Z: "+pointsOutput[i+2]);
		}
	}

And the glsl code:

#version 430

layout(local_size_x=1,local_size_y=1,local_size_z=1) in;

layout(std430, binding=0) buffer output_buffer
{
	vec4 points[];//Vec3 will also be aligned as vec4!!!!
};

layout (binding = 1) uniform sampler2D fragCoordMap;

void main()
{
	float zvalue=1.0*textureLod(fragCoordMap,vec2(0,0),0).x;
	points[0]=vec4(textureLod(fragCoordMap,vec2(0,0),0).xy,zvalue,1.0);

}

So…The first problem is: All values of the texture are 0.0 . I tested the texture exactly before dispatching the compute and all values were written. Also in the shader I can read the correct texturesize without problems.
Second: For some reason I can maximal use two values from the texture in the vec4 constructor. Everything else causes, that there is no value in the feedbackbuffer.
Means:

points[0]=vec4(textureLod(fragCoordMap,vec2(0,0),0).xy,zvalue,1.0);

works!
But

        float zvalue=1.0*textureLod(fragCoordMap,vec2(0,0),0).x;
	points[0]=vec4(textureLod(fragCoordMap,vec2(0,0),0).xy,zvalue,1.0);
or
        points[0]=vec4(textureLod(fragCoordMap,vec2(0,0),0).xyz,1.0);

doesn’t work!

First I thought it’s caused by mipmapping, but this should be fixed by the Usage of the Lod-function;

I hope you can help me!

Thank you in Advance

Destranix

(P.S.: In some points my code might not be optimized…That’s cause I’m not yet ready with it…So please don’t care about performance issues…)