我在GitHub上分叉了一个OpenSourced项目，并希望添加对几何着色器的支持。
这是我正在使用的OpenGL片段代码。
这两个着色器（片段和顶点着色器）用于“每像素照明”计算（可能存在错误）
片段着色器
setcolorder顶点着色器
library(data.table) ## V 1.9.5+
dt[elev <= 4 & shift(elev, type = "lead") > 4, Wave := "Rising"]
dt[elev > 4 & shift(elev, type = "lead") <= 4, Wave := "Falling"]
dcast(na.omit(dt), cumsum(Wave == "Rising") ~ Wave, value.var = "time")
# Wave Falling Rising
# 1: 1 2001-01-01 17:00:00 2001-01-01 10:00:00
# 2: 2 2001-01-02 03:00:00 2001-01-01 21:00:00
# 3: 3 2001-01-02 18:00:00 2001-01-02 11:00:00
基于这两个着色器，有人可以告诉我如何正确编写几何着色器。 我尝试了一些东西，但是我总是从几何着色器中得到关于“gl_FragColor”
的错误#ifdef USE_SHADOW_CUBEMAP
#ifdef USE_SHADOW_CUBESHADOWSAMPLER
#version 130
#extension GL_EXT_gpu_shader4 : enable
#endif // USE_SHADOW_CUBESHADOWSAMPLER
#endif
// shader input
uniform sampler2D colorMap;
uniform vec3 u_lightOrigin;
uniform float u_lightRadius;
// shader varying variables
varying vec3 v_vertXYZ;
varying vec3 v_vertNormal;
#if defined(HAS_BUMP_MAP) || defined(HAS_HEIGHT_MAP)
//Dushan - only supported in vertex shader
//attribute vec3 atrTangents;
//attribute vec3 atrBinormals;
varying mat3 tbnMat;
#endif
#ifdef HAS_BUMP_MAP
uniform sampler2D bumpMap;
#endif
#ifdef HAS_HEIGHT_MAP
uniform sampler2D heightMap;
varying vec3 v_tbnEyeDir;
#endif
#if defined(HAS_HEIGHT_MAP) && defined(USE_RELIEF_MAPPING)
#include "reliefMappingRaycast.inc"
#endif
#ifdef HAS_LIGHT_COLOR
uniform vec3 u_lightColor;
#endif
#ifdef ENABLE_SHADOW_MAPPING_BLUR
uniform float u_shadowMapSize;
#endif
#ifdef ENABLE_SHADOW_MAPPING_BLUR
float doShadowBlurSample(sampler2DShadow map, vec4 coord)
{
float shadow = 0.0;
float pixelOffset = 1.0/u_shadowMapSize;
//float samples = 0;
// avoid counter shadow
if (coord.w > 1.0)
{
float x,y;
for (y = -1.5; y <=1.5; y+=1.0)
{
for (x = -1.5; x <=1.5; x+=1.0)
{
//if(
//continue;
vec4 c = coord + vec4(x * pixelOffset * coord.w, y * pixelOffset * coord.w, 0, 0.0);
shadow += shadow2DProj(map, c ).w;
//samples += 1.0;
}
}
//shadow /= samples;
shadow /= 16;
}
return shadow;
}
#endif
#ifdef SHADOW_MAPPING_SPOTLIGHT
uniform sampler2DShadow spotLightShadowMap;
varying vec4 spotShadowCoord;
float computeSpotLightShadow() {
float shadow = 0;
#ifndef ENABLE_SHADOW_MAPPING_BLUR
shadow += shadow2DProj(spotLightShadowMap, spotShadowCoord).s;
#else
shadow += doShadowBlurSample(spotLightShadowMap, spotShadowCoord);
#endif
return shadow;
}
#elif defined(SHADOW_MAPPING_POINT_LIGHT)
uniform mat4 u_entityMatrix;
#ifdef USE_SHADOW_CUBEMAP
#ifdef USE_SHADOW_CUBESHADOWSAMPLER
uniform samplerCubeShadow shadowCubeMap;
#else
uniform samplerCube shadowCubeMap;
#endif
#else
varying vec4 shadowCoord0;
varying vec4 shadowCoord1;
varying vec4 shadowCoord2;
varying vec4 shadowCoord3;
varying vec4 shadowCoord4;
varying vec4 shadowCoord5;
uniform sampler2DShadow shadowMap0;
uniform sampler2DShadow shadowMap1;
uniform sampler2DShadow shadowMap2;
uniform sampler2DShadow shadowMap3;
uniform sampler2DShadow shadowMap4;
uniform sampler2DShadow shadowMap5;
int cubeSide(vec3 v) {
vec3 normals[] = { vec3(1,0,0), vec3(-1,0,0),
vec3(0,-1,0), vec3(0,1,0),
vec3(0,0,-1), vec3(0,0,1)};
float max = 0;
int ret;
for(int i = 0; i < 6; i++) {
float d = dot(normals[i],v);
if(d < max) {
max = d;
ret = i;
}
}
return ret;
}
#endif
uniform vec3 u_viewOrigin;
float computeShadow(vec3 lightToVertDirection) {
float shadow = 0.0;
#ifdef USE_SHADOW_CUBEMAP
#ifdef USE_SHADOW_CUBESHADOWSAMPLER
vec4 res = shadowCube( shadowCubeMap, vec4(-lightToVertDirection.x,lightToVertDirection.y,lightToVertDirection.z,depth) );
shadow = res.z;
#else
float shadowMapDist = textureCube(shadowCubeMap,vec3(-lightToVertDirection.x,lightToVertDirection.y,lightToVertDirection.z)).x;
float currentLenght = length(lightToVertDirection);
shadowMapDist *= u_lightRadius;
float eps = 0.0;
if(shadowMapDist + eps < currentLenght) {
shadow = 0.0;
} else {
shadow = 1.0;
}
#endif
#else
int side = cubeSide(lightToVertDirection);
#ifndef ENABLE_SHADOW_MAPPING_BLUR
if (side == 0) {
shadow += shadow2DProj(shadowMap0, shadowCoord0).s;
} else if(side == 1) {
shadow += shadow2DProj(shadowMap1, shadowCoord1).s;
} else if(side == 2) {
shadow += shadow2DProj(shadowMap2, shadowCoord2).s;
} else if(side == 3) {
shadow += shadow2DProj(shadowMap3, shadowCoord3).s;
} else if(side == 4) {
shadow += shadow2DProj(shadowMap4, shadowCoord4).s;
} else if(side == 5) {
shadow += shadow2DProj(shadowMap5, shadowCoord5).s;
} else {
// never gets here
}
#else
if (side == 0) {
shadow += doShadowBlurSample(shadowMap0, shadowCoord0);
} else if(side == 1) {
shadow += doShadowBlurSample(shadowMap1, shadowCoord1);
} else if(side == 2) {
shadow += doShadowBlurSample(shadowMap2, shadowCoord2);
} else if(side == 3) {
shadow += doShadowBlurSample(shadowMap3, shadowCoord3);
} else if(side == 4) {
shadow += doShadowBlurSample(shadowMap4, shadowCoord4);
} else if(side == 5) {
shadow += doShadowBlurSample(shadowMap5, shadowCoord5);
} else {
// never gets here
}
#endif
#endif
return shadow;
}
#endif // SHADOW_MAPPING_POINT_LIGHT
#ifdef LIGHT_IS_SPOTLIGHT
uniform vec3 u_lightDir;
uniform float u_spotLightMaxCos;
#endif
// #ifdef HAS_DOOM3_ALPHATEST
// uniform float u_alphaTestValue;
// #endif
void main() {
#if 0
gl_FragColor.rgb = v_vertNormal;
return;
#endif
// calculate texcoord
#ifdef HAS_HEIGHT_MAP
vec3 eyeDirNormalized = normalize(v_tbnEyeDir);
#ifdef USE_RELIEF_MAPPING
// relief mapping
vec2 texCoord = ReliefMappingRayCast(gl_TexCoord[0].xy,eyeDirNormalized);
#else
// simple height mapping
vec4 offset = texture2D(heightMap, gl_TexCoord[0].xy);
offset = offset * 0.05 - 0.02;
vec2 texCoord = offset.xy * eyeDirNormalized.xy + gl_TexCoord[0].xy;
#endif
#else
vec2 texCoord = gl_TexCoord[0].st;
#endif
// calculate light direction and distance to current pixel
vec3 lightToVert = u_lightOrigin - v_vertXYZ;
float distance = length(lightToVert);
if(distance > u_lightRadius) {
// pixel is too far from the ligh
return;
}
vec3 lightDirection = normalize(lightToVert);
#ifdef LIGHT_IS_SPOTLIGHT
float spotDOT = dot(lightDirection,u_lightDir);
if(-spotDOT < u_spotLightMaxCos) {
return;
}
#endif
#ifdef HAS_BUMP_MAP
vec3 bumpMapNormal = texture2D (bumpMap, texCoord).xyz;
bumpMapNormal = (bumpMapNormal - 0.5) * 2.0;
vec3 useNormal = tbnMat * bumpMapNormal;
#else
vec3 useNormal = v_vertNormal;
#endif
// calculate the diffuse value based on light angle
float angleFactor = dot(useNormal, lightDirection);
#ifdef MATERIAL_TWO_SIDED
angleFactor = abs(angleFactor);
#endif
if(angleFactor < 0.0) {
// light is behind the surface
return;
}
#ifdef DEBUG_IGNOREANGLEFACTOR
angleFactor = 1.0;
#endif // DEBUG_IGNOREANGLEFACTOR
// apply distnace scale
float distanceFactor = 1.0 - distance / u_lightRadius;
#ifdef DEBUG_IGNOREDISTANCEFACTOR
distanceFactor = 1.0;
#endif // DEBUG_IGNOREDISTANCEFACTOR
#ifdef SHADOW_MAPPING_POINT_LIGHT
vec4 lightWorld = (u_entityMatrix) * vec4(u_lightOrigin,1);
vec4 vertWorld = (u_entityMatrix) * vec4(v_vertXYZ,1);
vec4 lightToVert_world = lightWorld - vertWorld;
float shadow = computeShadow(lightToVert_world.xyz);
#elif defined(SHADOW_MAPPING_SPOTLIGHT)
float shadow = computeSpotLightShadow();
#else
float shadow = 1.0;
#endif
// testing
//#ifdef MATERIAL_TWO_SIDED
//angleFactor = 1.f;
//distanceFactor = 1.f;
//#endif
vec4 textureColor = texture2D (colorMap, texCoord);
// #ifdef HAS_DOOM3_ALPHATEST
// if(textureColor.a < u_alphaTestValue)
// {
// discard;
// }
// #endif
// calculate the final color
gl_FragColor = textureColor * angleFactor * distanceFactor * shadow;
#ifdef HAS_LIGHT_COLOR
gl_FragColor.xyz *= u_lightColor;
#endif
//gl_FragColor = textureCube(shadowCubeMap,vec3(-lightToVert_world.x,lightToVert_world.y,lightToVert_world.z));
#if defined(DEBUG_SHOW_SPOTLIGHT_SHADOWS) && defined(SHADOW_MAPPING_SPOTLIGHT)
if(shadow < 0.5) {
gl_FragColor += vec4(1,0,0,1);
}
#endif
#if defined(DEBUG_SHOW_POINTLIGHT_SHADOWS) && defined(SHADOW_MAPPING_POINT_LIGHT)
if(shadow < 0.5) {
gl_FragColor += vec4(0,1,0,1);
}
#endif
}
我是几何着色器的绝对新手，过去我从来没有使用它，请记住这一点。
我希望有人向我展示正确方法的例子，解释如何以及应该做些什么。
非常感谢
答案 0 :(得分：1)
gl_FragColor仅在片段着色器中可用，而不是几何着色器。