LWGL // 在片段着色器中重建位置

Question

我有正确的逆投影矩阵。但似乎没有什么是对的！ 重建的位置是否完全变形，z 值是否太小？有人建议吗？

vec3 calculatePosition(vec2 coord, float depth)
{ 
vec4 clipSpaceLocation;
clipSpaceLocation.x = coord.x * 2.0 - 1.0;
clipSpaceLocation.y = coord.y * 2.0 - 1.0;
clipSpaceLocation.z = depth * 2.0 - 1.0;
clipSpaceLocation.w = 1.0;
vec4 homogenousPosition = uProjectionInverse * clipSpaceLocation;

return homogenousPosition.xyz / homogenousPosition.w;
}

z 值约为 -0,001；为什么会这样？

坐标和深度是：

vec2 coord = vec2(gl_FragCoord.x / width, gl_FragCoord.y / height);
float currentDepth = texture(depthBuffer, coord).r;

我必须为大学实施 SSAO，并且我使用 Eclipse 和 Java 以及 lwjgl-plugin。 请我需要帮助。我不到一星期。

编辑： 我现在已经尝试过了……但仍然没有被 lenearized：

float camera_space_z_from_depth(sampler2D depthbuffer, vec2 uv) {
    float depth = texture(depthbuffer, uv).x;
    return (2 * uNearPlane) / (uFarPlane + uNearPlane - depth * (uFarPlane -       uNearPlane));
}

vec3 calculatePosition(vec2 coord, float depth)
{   
    vec4 clipSpaceLocation;
    clipSpaceLocation.x = coord.x * 2.0 - 1.0;
    clipSpaceLocation.y = coord.y * 2.0 - 1.0;
    clipSpaceLocation.z = depth * 2.0 - 1.0;
    clipSpaceLocation.w = 1.0;
   vec4 homogenousPosition = uProjectionInverse * clipSpaceLocation;

   return homogenousPosition.xyz / homogenousPosition.w;
}
vec3 getPosition(vec2 coord){
    float currentDepth = camera_space_z_from_depth(depthBuffer,coord);  
    vec3 position = calculatePosition(coord, currentDepth);
    return position;
}

Answer 1

我想你需要线性化你的深度值，就像这里说的：

https://www.opengl.org/wiki/Compute_eye_space_from_window_space

试试这个。

float camera_space_z_from_depth(sampler2D depthbuffer, vec2 uv) {
    const float depth = texture(depthbuffer, uv).x;
    return ( camera_near / (camera_far - depth * (camera_far - camera_near)) ) * camera_far;
}

编辑：

试试看。变量含义应该是不言自明的（不需要线性化）:)

vec3 GetPosition(vec2 fragmentCoordinates, float depth)
{
    vec3 normalizedDeviceCoordinatesPosition;
    normalizedDeviceCoordinatesPosition.xy = (2.0 * fragmentCoordinates) / uScreenSize - 1;
    normalizedDeviceCoordinatesPosition.z = 2.0 * depth - 1.0;

    vec4 clipSpacePosition;
    clipSpacePosition.w = uProjection[3][2] / (normalizedDeviceCoordinatesPosition.z - (uProjection[2][2] / uProjection[2][3]));
    clipSpacePosition.xyz = normalizedDeviceCoordinatesPosition * clipSpacePosition.w;

    vec4 eyePosition = uInverseProjection * clipSpacePosition;

    return eyePosition.xyz / eyePosition.w;
}

注意：到目前为止，我假设您的深度纹理是 GL_DEPTH_COMPONENT，并作为 GL_DEPTH_ATTACHMENT 附加到帧缓冲区。

即：

glBindTexture(GL_TEXTURE_2D, mDepthTextureId);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, mrScreenWidth, mrScreenHeight, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_NONE);
glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, mDepthTextureId, 0);