opengl - 写入浮点 FBO 时的低精度和钳位

Question

我有一个按以下方式创建的 FBO:

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);
}

如果我读出这样的像素:

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

并检查由上述片段程序写入的像素，它们是 (1, 1, 1, 1)。我只添加了 glReadPixels出于测试目的，如果我尝试使用 textureRect 在另一个片段程序中对 FBO 进行采样，我会遇到同样的问题。 .

Answer 1

是的，它将被限制在 (0, 1) 范围内 - 查看 glClampColor并禁用颜色钳制。

希望这可以帮助!