写入浮点FBO时精度低,钳位

Question

我有一个FBO,它是通过以下方式创建的:

glGenRenderbuffers(1, &m_depthStencilBuffer);
glBindRenderbuffer(GL_RENDERBUFFER, m_depthStencilBuffer);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_STENCIL, m_width, m_height);
glBindRenderbuffer(GL_RENDERBUFFER, 0);

glGenTextures(1, &m_texture);
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, m_texture);
glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA32F_ARB, m_width, m_height, 0, GL_RGBA, GL_FLOAT, 0);
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);

glGenFramebuffers(1, &m_frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, m_frameBuffer);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_RECTANGLE_ARB, m_texture, 0);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_depthStencilBuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, m_depthStencilBuffer);
assert(GL_FRAMEBUFFER_COMPLETE == glCheckFramebufferStatus(GL_FRAMEBUFFER));
glBindFramebuffer(GL_FRAMEBUFFER, 0);
assert(GL_NO_ERROR == glGetError());

然后我用这个最小的片段程序渲染到这个:

void main() {
    gl_FragColor = float4(3.001001f, 2.00002f, 7.00003f, 4.00004f);
}

如果我读出像这样的像素:

glReadPixels(0, 0, width, height, GL_RGBA, GL_FLOAT, &pixels[0]);

并检查上面的片段程序写入的像素(1,1,1,1).我只是glReadPixels为测试目的添加了,如果我尝试在另一个片段程序中对FBO进行采样,我会遇到同样的问题textureRect.

Answer 1

是的,它将被钳位到范围(0,1) - 检查glClampColor并禁用颜色钳制.

希望这可以帮助!