我正在尝试通过本教程实现此版本的ssao:
http://www.learnopengl.com/#!Advanced-Lighting/SSAO
这就是我渲染纹理的最终结果。
当我移动相机时,阴影似乎随之而来
好像我缺少相机的某种矩阵乘法。
码
gBuffer顶点
#version 330 core
layout (location = 0) in vec3 vertexPosition;
layout (location = 1) in vec3 vertexNormal;
out vec3 position;
out vec3 normal;
uniform mat4 m;
uniform mat4 v;
uniform mat4 p;
uniform mat4 n;
void main()
{
vec4 viewPos = v * m * vec4(vertexPosition, 1.0f);
position = viewPos.xyz;
gl_Position = p * viewPos;
normal = vec3(n * vec4(vertexNormal, 0.0f));
}
gBuffer片段
#version 330 core
layout (location = 0) out vec4 gPosition;
layout (location = 1) out vec3 gNormal;
layout (location = 2) out vec4 gColor;
in vec3 position;
in vec3 normal;
const float NEAR = 0.1f;
const float FAR = 50.0f;
float LinearizeDepth(float depth)
{
float z = depth * 2.0f - 1.0f;
return (2.0 * NEAR * FAR) / (FAR + NEAR - z * (FAR - NEAR));
}
void main()
{
gPosition.xyz = position;
gPosition.a = LinearizeDepth(gl_FragCoord.z);
gNormal = normalize(normal);
gColor.rgb = vec3(1.0f);
}
SSAO顶点
#version 330 core
layout (location = 0) in vec3 vertexPosition;
layout (location = 1) in vec2 texCoords;
out vec2 UV;
void main(){
gl_Position = vec4(vertexPosition, 1.0f);
UV = texCoords;
}
SSAO片段
#version 330 core
out float FragColor;
in vec2 UV;
uniform sampler2D gPositionDepth;
uniform sampler2D gNormal;
uniform sampler2D texNoise;
uniform vec3 samples[32];
uniform mat4 projection;
// parameters (you'd probably want to use them as uniforms to more easily tweak the effect)
int kernelSize = 32;
float radius = 1.0;
// tile noise texture over screen based on screen dimensions divided by noise size
const vec2 noiseScale = vec2(1024.0f/4.0f, 1024.0f/4.0f);
void main()
{
// Get input for SSAO algorithm
vec3 fragPos = texture(gPositionDepth, UV).xyz;
vec3 normal = texture(gNormal, UV).rgb;
vec3 randomVec = texture(texNoise, UV * noiseScale).xyz;
// Create TBN change-of-basis matrix: from tangent-space to view-space
vec3 tangent = normalize(randomVec - normal * dot(randomVec, normal));
vec3 bitangent = cross(normal, tangent);
mat3 TBN = mat3(tangent, bitangent, normal);
// Iterate over the sample kernel and calculate occlusion factor
float occlusion = 0.0;
for(int i = 0; i < kernelSize; ++i)
{
// get sample position
vec3 sample = TBN * samples[i]; // From tangent to view-space
sample = fragPos + sample * radius;
// project sample position (to sample texture) (to get position on screen/texture)
vec4 offset = vec4(sample, 1.0);
offset = projection * offset; // from view to clip-space
offset.xyz /= offset.w; // perspective divide
offset.xyz = offset.xyz * 0.5 + 0.5; // transform to range 0.0 - 1.0
// get sample depth
float sampleDepth = -texture(gPositionDepth, offset.xy).w; // Get depth value of kernel sample
// range check & accumulate
float rangeCheck = smoothstep(0.0, 1.0, radius / abs(fragPos.z - sampleDepth ));
occlusion += (sampleDepth >= sample.z ? 1.0 : 0.0) * rangeCheck;
}
occlusion = 1.0 - (occlusion / kernelSize);
FragColor = occlusion;
}
我已经阅读了一遍,看到有人遇到了类似的问题,并将视图矩阵传递到了sao着色器中,并将sampleDepth乘以:
float sampleDepth = (viewMatrix * -texture(gPositionDepth, offset.xy)).w;
但似乎只会使情况变得更糟。
这是从上到下的另一个视图,您可以在其中看到阴影随相机移动
如果我以某些方式放置相机,一切都会对齐
最佳答案
尽管我只能在gBuffer顶点着色器中假定法线矩阵n
的值,但似乎您没有将法线存储在视图空间中,而是存储在世界空间中。由于SSAO计算是在屏幕空间中完成的,因此可以(至少部分地)解释意外行为。在这种情况下,您需要先将视图矩阵v
乘以法线,然后再将其存储到gBuffer(可能更有效,但可能会干扰其他阴影计算)或在检索它们之后。