tom w

I've been developing a project over some time between my two machines - one is a Macbook Pro, the other is an iMac.

The application uses a few custom shaders, which have always run fine on the Macbook Pro and iMac. I've now come to deploy this application on a Mac Pro, and some of my shaders are no longer working. I wondered if anybody could shed some light on what the matter might be?

texcoord0 = vec2(gl_TextureMatrix[0] * gl_MultiTexCoord0);

texcoord1 = vec2(gl_TextureMatrix[1] * gl_MultiTexCoord1);

// extract the x and y scalars from the texture matrix to determine dimensions

texdim0 = vec2 (abs(gl_TextureMatrix[0][0][0]),abs(gl_TextureMatrix[0][1][1]));

texdim1 = vec2 (abs(gl_TextureMatrix[1][0][0]),abs(gl_TextureMatrix[1][1][1]));

texorient0 = vec2 (gl_TextureMatrix[0][0][0]/texdim0.x,gl_TextureMatrix[0][1][1]/texdim0.y);

texorient1 = vec2 (gl_TextureMatrix[1][0][0]/texdim1.x,gl_TextureMatrix[1][1][1]/texdim1.y);

uniform sampler2DRect tex0; // VelocityTexture

uniform sampler2DRect tex1; // SourceTexture

    vec2 u = texture2DRect(tex0,texcoord0).xy;

    vec2 srccoord = fragCoord - (TimeStep * u);

    vec4 samplevalue = Dissipation * texture2DRect(tex1,srccoord);

    gl_FragColor = vec4(samplevalue.x,samplevalue.y,samplevalue.z,1.);

Macbook Pro NVIDIA GeForce GT 650M 1024 MB - works

iMac, 27" late 2012 NVIDIA GeForce GTX 680MX 2048 MB - works

Mac Pro, Dual AMD FirePro D500 graphics processors with 3GB of GDDR5 VRAM - doesn't work

I've been developing a project over some time between my two machines - one is a Macbook Pro, the other is an iMac. 

varying vec2 texcoord0;
varying vec2 texcoord1;
varying vec2 texdim0;
varying vec2 texdim1;
varying vec2 texorient0;
varying vec2 texorient1;

void main()
{
    // perform standard transform on vertex
    gl_Position = ftransform();

    // transform texcoords
    texcoord0 = vec2(gl_TextureMatrix[0] * gl_MultiTexCoord0);
    texcoord1 = vec2(gl_TextureMatrix[1] * gl_MultiTexCoord1);
    // extract the x and y scalars from the texture matrix to determine dimensions
    texdim0 = vec2 (abs(gl_TextureMatrix[0][0][0]),abs(gl_TextureMatrix[0][1][1]));
    texdim1 = vec2 (abs(gl_TextureMatrix[1][0][0]),abs(gl_TextureMatrix[1][1][1]));
    // extract the sign for orientation
    texorient0 = vec2 (gl_TextureMatrix[0][0][0]/texdim0.x,gl_TextureMatrix[0][1][1]/texdim0.y);
    texorient1 = vec2 (gl_TextureMatrix[1][0][0]/texdim1.x,gl_TextureMatrix[1][1][1]/texdim1.y);
} 

<<<<<< pixel  >>>>>
uniform sampler2DRect tex0; // VelocityTexture
uniform sampler2DRect tex1; // SourceTexture

uniform float TimeStep;
uniform float Dissipation;

varying vec2 texcoord0;
varying vec2 texcoord1;
varying vec2 texdim0;
varying vec2 texdim1;

void main()
{
	vec2 u = texture2DRect(tex0,texcoord0).xy;
        vec2 fragCoord = gl_FragCoord.xy;
	vec2 srccoord = fragCoord - (TimeStep * u);
	vec4 samplevalue = Dissipation * texture2DRect(tex1,srccoord);
	gl_FragColor = vec4(samplevalue.x,samplevalue.y,samplevalue.z,1.);
}

Macbook Pro NVIDIA GeForce GT 650M 1024 MB - works
iMac, 27" late 2012 NVIDIA GeForce GTX 680MX 2048 MB - works
Mac Pro, Dual AMD FirePro D500 graphics processors with 3GB of GDDR5 VRAM - doesn't work


gl-shader-problem-on-mac-pro

Having a similar problem with jit.gl.pix. It seems that if, in a shader with several input textures, these textures do not have the same dimensions, the output is not correct on a MacPro. Maybe because of AMD graphic processor?

One solution could be to use textures with same dim and to pass dim info into parameter.

Thanks for the response JMC - and the solidarity! I think both textures are the same dimension in my patch but will check. I've also removed the gl_FragCoord call as I have seen mention of problems with this function, and it appears to be duplicating the work done in the fragment shader anyway.

GL Shader problem on Mac Pro