Saya mencoba untuk melakukan shading ubin yang ditangguhkan di OpenGL menggunakan compute shader tapi saya telah mendapatkan kesulitan ketika mencoba untuk membuat frustum untuk setiap ubin. Saya menggunakan demo Forward + AMD (ditulis dalam D3D) sebagai panduan tetapi lampu tampaknya dimusnahkan ketika seharusnya tidak.
MEMPERBARUI
Baca di bawah untuk pembaruan.
Ini adalah penghitung komputasi saya (lengkap):
#version 430 core
#define MAX_LIGHTS 1024
#define MAX_LIGHTS_PER_TILE 40
#define WORK_GROUP_SIZE 16
struct PointLight
{
vec3 position;
float radius;
vec3 color;
float intensity;
};
layout (binding = 0, rgba32f) uniform writeonly image2D outTexture;
layout (binding = 1, rgba32f) uniform readonly image2D normalDepth;
layout (binding = 2, rgba32f) uniform readonly image2D diffuse;
layout (binding = 3, rgba32f) uniform readonly image2D specular;
layout (binding = 4, rgba32f) uniform readonly image2D glowMatID;
layout (std430, binding = 5) buffer BufferObject
{
PointLight pointLights[];
};
uniform mat4 view;
uniform mat4 proj;
uniform mat4 viewProj;
uniform mat4 invViewProj;
uniform mat4 invProj;
uniform vec2 framebufferDim;
layout (local_size_x = WORK_GROUP_SIZE, local_size_y = WORK_GROUP_SIZE) in;
shared uint minDepth = 0xFFFFFFFF;
shared uint maxDepth = 0;
shared uint pointLightIndex[MAX_LIGHTS];
shared uint pointLightCount = 0;
vec3 ReconstructWP(float z, vec2 uv_f)
{
vec4 sPos = vec4(uv_f * 2.0 - 1.0, z, 1.0);
sPos = invViewProj * sPos;
return (sPos.xyz / sPos.w);
}
vec4 ConvertProjToView( vec4 p )
{
p = invProj * p;
p /= p.w;
return p;
}
// calculate the number of tiles in the horizontal direction
uint GetNumTilesX()
{
return uint(( ( 1280 + WORK_GROUP_SIZE - 1 ) / float(WORK_GROUP_SIZE) ));
}
// calculate the number of tiles in the vertical direction
uint GetNumTilesY()
{
return uint(( ( 720 + WORK_GROUP_SIZE - 1 ) / float(WORK_GROUP_SIZE) ));
}
vec4 CreatePlaneEquation( vec4 b, vec4 c )
{
vec4 n;
// normalize(cross( b.xyz-a.xyz, c.xyz-a.xyz )), except we know "a" is the origin
n.xyz = normalize(cross( b.xyz, c.xyz ));
// -(n dot a), except we know "a" is the origin
n.w = 0;
return n;
}
float GetSignedDistanceFromPlane( vec4 p, vec4 eqn )
{
// dot( eqn.xyz, p.xyz ) + eqn.w, , except we know eqn.w is zero
// (see CreatePlaneEquation above)
return dot( eqn.xyz, p.xyz );
}
vec4 CalculateLighting( PointLight p, vec3 wPos, vec3 wNormal, vec4 wSpec, vec4 wGlow)
{
vec3 direction = p.position - wPos;
if(length(direction) > p.radius)
return vec4(0.0f, 0.0f, 0.0f, 0.0f);
float attenuation = 1.0f - length(direction) / (p.radius);
direction = normalize(direction);
float diffuseFactor = max(0.0f, dot(direction, wNormal)) * attenuation;
return vec4(p.color.xyz, 0.0f) * diffuseFactor * p.intensity;
}
void main()
{
ivec2 pixelPos = ivec2(gl_GlobalInvocationID.xy);
vec2 tilePos = vec2(gl_WorkGroupID.xy * gl_WorkGroupSize.xy) / vec2(1280, 720);
vec4 normalColor = imageLoad(normalDepth, pixelPos);
float d = normalColor.w;
uint depth = uint(d * 0xFFFFFFFF);
atomicMin(minDepth, depth);
atomicMax(maxDepth, depth);
barrier();
float minDepthZ = float(minDepth / float(0xFFFFFFFF));
float maxDepthZ = float(maxDepth / float(0xFFFFFFFF));
vec4 frustumEqn[4];
uint pxm = WORK_GROUP_SIZE * gl_WorkGroupID.x;
uint pym = WORK_GROUP_SIZE * gl_WorkGroupID.y;
uint pxp = WORK_GROUP_SIZE * (gl_WorkGroupID.x + 1);
uint pyp = WORK_GROUP_SIZE * (gl_WorkGroupID.y + 1);
uint uWindowWidthEvenlyDivisibleByTileRes = WORK_GROUP_SIZE * GetNumTilesX();
uint uWindowHeightEvenlyDivisibleByTileRes = WORK_GROUP_SIZE * GetNumTilesY();
vec4 frustum[4];
frustum[0] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
frustum[1] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
frustum[2] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f ,1.0f) );
frustum[3] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
for (int i = 0; i < 4; i++)
frustumEqn[i] = CreatePlaneEquation(frustum[i], frustum[(i+1) & 3]);
barrier();
int threadsPerTile = WORK_GROUP_SIZE * WORK_GROUP_SIZE;
for (uint i = 0; i < MAX_LIGHTS; i+= threadsPerTile)
{
uint il = gl_LocalInvocationIndex + i;
if (il < MAX_LIGHTS)
{
PointLight p = pointLights[il];
vec4 viewPos = view * vec4(p.position, 1.0f);
float r = p.radius;
if (viewPos.z + minDepthZ < r && viewPos.z - maxDepthZ < r)
{
if( ( GetSignedDistanceFromPlane( viewPos, frustumEqn[0] ) < r ) &&
( GetSignedDistanceFromPlane( viewPos, frustumEqn[1] ) < r ) &&
( GetSignedDistanceFromPlane( viewPos, frustumEqn[2] ) < r ) &&
( GetSignedDistanceFromPlane( viewPos, frustumEqn[3] ) < r) )
{
uint id = atomicAdd(pointLightCount, 1);
pointLightIndex[id] = il;
}
}
}
}
barrier();
vec4 diffuseColor = imageLoad(diffuse, pixelPos);
vec4 specularColor = imageLoad(specular, pixelPos);
vec4 glowColor = imageLoad(glowMatID, pixelPos);
vec2 uv = vec2(pixelPos.x / 1280.0f, pixelPos.y / 720.0f);
vec3 wp = ReconstructWP(d, uv);
vec4 color = vec4(0.0f, 0.0f, 0.0f, 1.0f);
for (int i = 0; i < pointLightCount; i++)
{
color += CalculateLighting( pointLights[pointLightIndex[i]], wp, normalColor.xyz, specularColor, glowColor);
}
barrier();
if (gl_LocalInvocationID.x == 0 || gl_LocalInvocationID.y == 0 || gl_LocalInvocationID.x == 16 || gl_LocalInvocationID.y == 16)
imageStore(outTexture, pixelPos, vec4(.2f, .2f, .2f, 1.0f));
else
{
imageStore(outTexture, pixelPos, color);
//imageStore(outTexture, pixelPos, vec4(maxDepthZ));
//imageStore(outTexture, pixelPos, vec4(pointLightCount / 128.0f));
//imageStore(outTexture, pixelPos, vec4(vec2(tilePos.xy), 0.0f, 1.0f));
}
}
Ini adalah bagian yang saya pikir adalah masalahnya, bagian pemusnahan:
barrier();
float minDepthZ = float(minDepth / float(0xFFFFFFFF));
float maxDepthZ = float(maxDepth / float(0xFFFFFFFF));
vec4 frustumEqn[4];
uint pxm = WORK_GROUP_SIZE * gl_WorkGroupID.x;
uint pym = WORK_GROUP_SIZE * gl_WorkGroupID.y;
uint pxp = WORK_GROUP_SIZE * (gl_WorkGroupID.x + 1);
uint pyp = WORK_GROUP_SIZE * (gl_WorkGroupID.y + 1);
uint uWindowWidthEvenlyDivisibleByTileRes = WORK_GROUP_SIZE * GetNumTilesX();
uint uWindowHeightEvenlyDivisibleByTileRes = WORK_GROUP_SIZE * GetNumTilesY();
vec4 frustum[4];
frustum[0] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
frustum[1] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pym) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
frustum[2] = ConvertProjToView( vec4( pxp / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f ,1.0f) );
frustum[3] = ConvertProjToView( vec4( pxm / float(uWindowWidthEvenlyDivisibleByTileRes) * 2.0f - 1.0f, (uWindowHeightEvenlyDivisibleByTileRes - pyp) / float(uWindowHeightEvenlyDivisibleByTileRes) * 2.0f - 1.0f, 1.0f, 1.0f) );
for (int i = 0; i < 4; i++)
frustumEqn[i] = CreatePlaneEquation(frustum[i], frustum[(i+1) & 3]);
barrier();
int threadsPerTile = WORK_GROUP_SIZE * WORK_GROUP_SIZE;
for (uint i = 0; i < MAX_LIGHTS; i+= threadsPerTile)
{
uint il = gl_LocalInvocationIndex + i;
if (il < MAX_LIGHTS)
{
PointLight p = pointLights[il];
vec4 viewPos = view * vec4(p.position, 1.0f);
float r = p.radius;
if (viewPos.z + minDepthZ < r && viewPos.z - maxDepthZ < r)
{
if( ( GetSignedDistanceFromPlane( viewPos, frustumEqn[0] ) < r ) &&
( GetSignedDistanceFromPlane( viewPos, frustumEqn[1] ) < r ) &&
( GetSignedDistanceFromPlane( viewPos, frustumEqn[2] ) < r ) &&
( GetSignedDistanceFromPlane( viewPos, frustumEqn[3] ) < r) )
{
uint id = atomicAdd(pointLightCount, 1);
pointLightIndex[id] = il;
}
}
}
}
barrier();
Yang aneh adalah bahwa ketika saya memvisualisasikan jumlah cahaya per ubin, itu menunjukkan semua ubin memiliki beberapa jenis lampu (gambar pertama).
Gambar kedua menunjukkan hasil akhir, garis tipis lampu di tengah layar dan tidak ada yang di atas atau di bawah. Menghapus culling (GetSignedDistanceFromPlane ()) memberikan hasil yang diinginkan, meskipun framerate saya jatuh seperti batu.
Dugaan saya adalah bahwa frustum dibuat salah, tetapi saya tidak yakin dengan matematika di baliknya dan dapat menggunakan bantuan sekarang.
Sunting: Menambahkan gambar lain yang menunjukkan output yang diharapkan.
PEMBARUAN 1
Kami telah mengubah cara pemusnahan dilakukan, kode sekarang terlihat seperti ini:
barrier();
float minDepthZ = float(minDepth / float(0xFFFFFFFF));
float maxDepthZ = float(maxDepth / float(0xFFFFFFFF));
//total tiles = tileScale * 2
vec2 tileScale = vec2(1280, 720) * (1.0f / float(2*WORK_GROUP_SIZE));
vec2 tileBias = tileScale - vec2(gl_WorkGroupID.xy);
vec4 c1 = vec4(-proj[0][0] * tileScale.x, 0.0f, tileBias.x, 0.0f);
vec4 c2 = vec4(0.0f, -proj[1][1] * tileScale.y, tileBias.y, 0.0f);
vec4 c4 = vec4(0.0f, 0.0f, 1.0f, 0.0f);
// Derive frustum planes
vec4 frustumPlanes[6];
// Sides
//right
frustumPlanes[0] = c4 - c1;
//left
frustumPlanes[1] = c4 + c1;
//bottom
frustumPlanes[2] = c4 - c2;
//top
frustumPlanes[3] = c4 + c2;
// Near/far
frustumPlanes[4] = vec4(0.0f, 0.0f, 1.0f, -minDepthZ);
frustumPlanes[5] = vec4(0.0f, 0.0f, -1.0f, maxDepthZ);
for(int i = 0; i < 4; i++)
{
frustumPlanes[i] *= 1.0f / length(frustumPlanes[i].xyz);
}
//DO CULLING HERE
for (uint lightIndex = gl_LocalInvocationIndex; lightIndex < numActiveLights; lightIndex += WORK_GROUP_SIZE)
{
PointLight p = pointLights[lightIndex];
if (lightIndex < numActiveLights)
{
bool inFrustum = true;
for (uint i = 0; i < 4; i++)
{
float dd = dot(frustumPlanes[i], view * vec4(p.position, 1.0f));
inFrustum = inFrustum && (dd >= -p.radius_length);
}
if (inFrustum)
{
uint id = atomicAdd(pointLightCount, 1);
pointLightIndex[id] = lightIndex;
}
}
}
barrier();
Ini berfungsi lebih baik, lampu kami sekarang dimusnahkan dengan benar (kecuali kedalaman min / maks karena belum diterapkan dengan benar) terhadap ubin kami. Sejauh ini, sangat bagus, TAPI! Kami memiliki masalah dengan tepi lampu, ubin tidak menutupi seluruh jari-jari cahaya dan kinerjanya luar biasa. 1024 lampu memberikan 40fps terbaik dengan ton gagap.
Video ini menunjukkan apa yang terjadi pada tepian, ubin abu-abu adalah ubin yang dipengaruhi oleh cahaya (titik tunggal) dan bagian merah adalah geometri yang diarsir.
http://www.youtube.com/watch?v=PiwGcFb9rWk&feature=youtu.be
Melakukan penskalaan jari-jari sehingga lebih besar saat memilih "bekerja" tetapi membuat kinerja turun lebih sulit.