how to do Vertex texture fetch for depth texture generated by FBO? is it possible?
Author
the following code generates the depth texture,using fbo depth attachment.
glGenTextures(1, &depthTextureID);
glBindTexture(GL_TEXTURE_2D, depthTextureID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glGenFramebuffersEXT(1, &framebufferID);
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, framebufferID);
// Set up some renderbuffer state
glGenRenderbuffersEXT(1, &renderbufferID);
glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, renderbufferID);
glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT32, 1024, 1024);
glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, renderbufferID);
glTexImage2D(GL_TEXTURE_2D, 0,GL_DEPTH_COMPONENT32, 1024, 1024, 0,GL_DEPTH_COMPONENT , GL_UNSIGNED_BYTE, NULL);
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT , GL_TEXTURE_2D, &depthTextureID);, 0);
glDrawBuffer(GL_NONE);
glReadBuffer(GL_NONE);
GLenum fboStatus = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
if (fboStatus != GL_FRAMEBUFFER_COMPLETE_EXT)
{
fprintf(stderr, "FBO Error!\n");
}
glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
today only the GL_LUMINANCE_FLOAT32_ATI or GL_RGBA_FLOAT32_ATI texture internalformat can be used for VTF(is it right?),then how can i use VTF for the generated depth texture.
if i use glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_FLOAT32_ATI , 1024, 1024, 0,GL_DEPTH_COMPONENT , GL_UNSIGNED_BYTE, NULL),then will get "FBO Error".
Thanks a lot
Its not strictly true that only GL_LUMINANCE_FLOAT32_ATI and GL_RGBA_FLOAT32_ATI are supported for ATI, it depends on the driver/card. For one, I know that some non-floating point formats are supported on current NVIDIA Mac drivers.
GL_LUMINANCE_FLOAT32_ATI or GL_RGBA_FLOAT32_ATI are part the old extension. Feel free to move up to GL_ARB_texture_float
As far as supported formats, it depends on the GPU. I don't know what Gf8 and Gf9 support.
Certain ATI cards will return 0 for
glGetIntegerv(GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS, &MaxVertexTextureImageUnits);
You can use GL_DEPTH_COMPONENT32 and it will work except it will run the vertex shader in software mode.
As far as supported formats, it depends on the GPU. I don't know what Gf8 and Gf9 support.
Certain ATI cards will return 0 for
glGetIntegerv(GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS, &MaxVertexTextureImageUnits);
You can use GL_DEPTH_COMPONENT32 and it will work except it will run the vertex shader in software mode.
Author
Thanks V-Man
i use Geforce 7300 card,
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32, 1024, 1024, 0,GL_DEPTH_COMPONENT , GL_UNSIGNED_BYTE, NULL);
Now the depth texture internalformat is GL_DEPTH_COMPONENT32.Because VTF need
GL_RGBA32F_ARB or GL_LUMINANCE32F_ARB,so the depth texture couldnot be used for VTF.Is it right?
The conclusion that depth texture couldnot be used for VTF is right or not?
i use Geforce 7300 card,
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT32, 1024, 1024, 0,GL_DEPTH_COMPONENT , GL_UNSIGNED_BYTE, NULL);
Now the depth texture internalformat is GL_DEPTH_COMPONENT32.Because VTF need
GL_RGBA32F_ARB or GL_LUMINANCE32F_ARB,so the depth texture couldnot be used for VTF.Is it right?
The conclusion that depth texture couldnot be used for VTF is right or not?
If this returns a non-zero value
glGetIntegerv(GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS, &MaxVertexTextureImageUnits);
then you can use vertex texture fetch. That's all that GL tells you.
If the GPU supports GL_DEPTH_COMPONENT32 sampling from your VS, then it is ok.
If not, it will run in software mode.
glGetIntegerv(GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS, &MaxVertexTextureImageUnits);
then you can use vertex texture fetch. That's all that GL tells you.
If the GPU supports GL_DEPTH_COMPONENT32 sampling from your VS, then it is ok.
If not, it will run in software mode.
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