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我想做一个简单的CG任务：在六面绘制一个具有纹理的天空图立方体。已经阅读了很多教程，但是纹理存在一些问题。立方体的所有6边都是完全黑色的（但是如果我在片段着色器中用简单的vec4（1.0f，...）调用纹理（..）调用，则墙体将被着色，所以它必须是纹理）。OpenGL GL_TEXTURE_CUBE_MAP没有纹理/黑色
所以，这里是我在做什么的摘录：
void SkyCube::init() {
mShader = new Shader("./Shader/skybox.vs", "./Shader/skybox.fs");
// from: https://www.opengl.org/wiki/Common_Mistakes#Creating_a_Cubemap_Texture
glEnable(GL_TEXTURE_CUBE_MAP);
glGenTextures(1, &mTextureId);
glBindTexture(GL_TEXTURE_CUBE_MAP, mTextureId);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAX_LEVEL, 0);
// now load the textures from TGA files and make them available to OpenGL
TgaLoader * tgaLoader = new TgaLoader();
string texturefilenames[] = {"back", "front", "bottom", "top", "left", "right"};
int texturedefs[] = {GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y,
GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z};
for (int i = 0; i < 6; i++) {
tgaLoader->loadTga(mTextures[i], "data/skycube/" + texturefilenames[i] + ".tga");
glTexImage2D(texturedefs[i], 0, GL_RGB, mTextures[i].width, mTextures[i].height,
0, GL_BGR, GL_UNSIGNED_BYTE, mTextures[i].imageData);
}
delete tgaLoader;
mVboSkyCube = this->generateSkyCubeVBO(vec3(-1.0f, -1.0f, -1.0f), vec3(1.0f, 1.0f, 1.0f));
glDisable(GL_TEXTURE_CUBE_MAP);
}
的generateSkyCubeVBO方法基本上生成所有的顶点和纹理归一化坐标：
VertexBufferObjectAttribs* SkyCube::generateSkyCubeVBO(const vec3 &mi, const vec3 &ma) {
vector<vec3> vertices;
vector<vec3> normals;
vector<vec2> textureUV;
// tofo liste mit texture koords
// 00 01
// 10 11
// 2d vec
vertices.push_back(vec3(mi.x, ma.y, mi.z));
vertices.push_back(vec3(mi.x, ma.y, ma.z));
vertices.push_back(vec3(ma.x, ma.y, ma.z));
vertices.push_back(vec3(ma.x, ma.y, mi.z));
normals.push_back(vec3(0.0f, 1.0f, 0.0f));
normals.push_back(vec3(0.0f, 1.0f, 0.0f));
normals.push_back(vec3(0.0f, 1.0f, 0.0f));
normals.push_back(vec3(0.0f, 1.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 1.0f));
textureUV.push_back(vec2(1.0f, 0.0f));
textureUV.push_back(vec2(1.0f, 1.0f));
vertices.push_back(vec3(mi.x, mi.y, mi.z));
vertices.push_back(vec3(ma.x, mi.y, mi.z));
vertices.push_back(vec3(ma.x, mi.y, ma.z));
vertices.push_back(vec3(mi.x, mi.y, ma.z));
normals.push_back(vec3(0.0f, -1.0f, 0.0f));
normals.push_back(vec3(0.0f, -1.0f, 0.0f));
normals.push_back(vec3(0.0f, -1.0f, 0.0f));
normals.push_back(vec3(0.0f, -1.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 1.0f));
textureUV.push_back(vec2(1.0f, 0.0f));
textureUV.push_back(vec2(1.0f, 1.0f));
vertices.push_back(vec3(mi.x, mi.y, mi.z));
vertices.push_back(vec3(mi.x, ma.y, mi.z));
vertices.push_back(vec3(ma.x, ma.y, mi.z));
vertices.push_back(vec3(ma.x, mi.y, mi.z));
normals.push_back(vec3(0.0f, 0.0f, -1.0f));
normals.push_back(vec3(0.0f, 0.0f, -1.0f));
normals.push_back(vec3(0.0f, 0.0f, -1.0f));
normals.push_back(vec3(0.0f, 0.0f, -1.0f));
textureUV.push_back(vec2(0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 1.0f));
textureUV.push_back(vec2(1.0f, 0.0f));
textureUV.push_back(vec2(1.0f, 1.0f));
vertices.push_back(vec3(mi.x, mi.y, ma.z));
vertices.push_back(vec3(ma.x, mi.y, ma.z));
vertices.push_back(vec3(ma.x, ma.y, ma.z));
vertices.push_back(vec3(mi.x, ma.y, ma.z));
normals.push_back(vec3(0.0f, 0.0f, 1.0f));
normals.push_back(vec3(0.0f, 0.0f, 1.0f));
normals.push_back(vec3(0.0f, 0.0f, 1.0f));
normals.push_back(vec3(0.0f, 0.0f, 1.0f));
textureUV.push_back(vec2(0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 1.0f));
textureUV.push_back(vec2(1.0f, 0.0f));
textureUV.push_back(vec2(1.0f, 1.0f));
vertices.push_back(vec3(mi.x, mi.y, mi.z));
vertices.push_back(vec3(mi.x, mi.y, ma.z));
vertices.push_back(vec3(mi.x, ma.y, ma.z));
vertices.push_back(vec3(mi.x, ma.y, mi.z));
normals.push_back(vec3(-1.0f, 0.0f, 0.0f));
normals.push_back(vec3(-1.0f, 0.0f, 0.0f));
normals.push_back(vec3(-1.0f, 0.0f, 0.0f));
normals.push_back(vec3(-1.0f, 0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 1.0f));
textureUV.push_back(vec2(1.0f, 0.0f));
textureUV.push_back(vec2(1.0f, 1.0f));
vertices.push_back(vec3(ma.x, mi.y, mi.z));
vertices.push_back(vec3(ma.x, ma.y, mi.z));
vertices.push_back(vec3(ma.x, ma.y, ma.z));
vertices.push_back(vec3(ma.x, mi.y, ma.z));
normals.push_back(vec3(1.0f, 0.0f, 0.0f));
normals.push_back(vec3(1.0f, 0.0f, 0.0f));
normals.push_back(vec3(1.0f, 0.0f, 0.0f));
normals.push_back(vec3(1.0f, 0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 0.0f));
textureUV.push_back(vec2(0.0f, 1.0f));
textureUV.push_back(vec2(1.0f, 0.0f));
textureUV.push_back(vec2(1.0f, 1.0f));
GLuint nrVertices = vertices.size();
VertexBufferObjectAttribs::DATA *attrData = new VertexBufferObjectAttribs::DATA[nrVertices];
for (GLuint i = 0; i < nrVertices; ++i) {
vec3 v = vertices[i];
vec3 n = normals[i];
vec2 t = textureUV[i];
attrData[i].vx = v.x;
attrData[i].vy = v.y;
attrData[i].vz = v.z;
attrData[i].vw = 1.0f;
attrData[i].nx = n.x;
attrData[i].ny = n.y;
attrData[i].nz = n.z;
attrData[i].nw = 0.0f;
attrData[i].tx = t.x;
attrData[i].ty = t.y;
attrData[i].tz = 0.0f;
attrData[i].tw = 0.0f;
}
VertexBufferObjectAttribs *vbo = new VertexBufferObjectAttribs();
vbo->setData(attrData, GL_STATIC_DRAW, nrVertices, GL_QUADS);
vbo->addAttrib(VERTEX_POSITION);
vbo->addAttrib(VERTEX_NORMAL);
vbo->addAttrib(VERTEX_COLOR);
vbo->addAttrib(VERTEX_TEXTURE);
vbo->bindAttribs();
delete[] attrData;
return vbo;
}
这工作正常，所有纹理成功加载。 顶点着色器：
// OpenGL 3.3
#version 130
// following is probably not really needed
#define VERT_POSITION 0
#define VERT_NORMAL 1
#define VERT_COLOR 2
#define VERT_TEXTURE 3
uniform mat4x4 matModel;
uniform mat4x4 matView;
uniform mat4x4 matProjection;
attribute vec4 Position;
attribute vec4 Normal;
attribute vec4 Color;
attribute vec4 Texture;
out vec4 VertPosition;
out vec4 VertNormal;
out vec4 VertColor;
out vec4 VertTexture;
void main()
{
VertPosition = Position;
VertNormal = Normal;
VertColor = Color;
VertTexture = Texture;
gl_Position = matProjection * matView * matModel * vec4(Position.xyz, 1);
}
片段着色器：
// OpenGL 3.3
#version 130
in vec4 VertPosition;
in vec4 VertNormal;
in vec4 VertColor;
in vec4 VertTexture; // Interpolated values from the vertex shaders, similar to the tutorial :-)
uniform vec3 lightPos;
uniform sampler2D skyBoxTextureSampler; // to know which texture to access, from the tutorial :-)
void main()
{
vec4 color = VertColor;
gl_FragColor = texture(skyBoxTextureSampler, VertTexture.xy); //vec4(1.0f, 1.0f, 0.9f, 1.0f); //
}
render方法：
void SkyCube::render(const Transform& trans) {
mat4 projection = trans.projection;
mat4 view = trans.view;
mat4 model = mat4::identitiy();
glPushAttrib(GL_ALL_ATTRIB_BITS);
glPushClientAttrib(GL_CLIENT_ALL_ATTRIB_BITS);
glEnable(GL_TEXTURE_CUBE_MAP);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_CUBE_MAP, mTextureId);
mShader->bind();
mShader->setMatrix("matProjection", projection, GL_TRUE);
mShader->setMatrix("matView", view, GL_TRUE);
// mShader->setMatrix("Texture")
model = mat4::scale(20.0f, 20.0f, 20.0f);
mShader->setMatrix("matModel", model, GL_TRUE);
// set the texture
mShader->seti("skyBoxTextureSampler", 0);
mVboSkyCube->render();
mShader->release();
glPopClientAttrib();
glPopAttrib();
}
渲染的VBO对象的方法是这样的：
void VertexBufferObjectAttribs::render() {
GLint size = m_attribLocations.size();
glBindBuffer(GL_ARRAY_BUFFER, m_bufferId);
for (GLint i = 0; i < size; ++i) {
GLint attribLoc = m_attribLocations[i];
glVertexAttribPointer(attribLoc, 4, GL_FLOAT, GL_FALSE, sizeof (DATA), ((GLchar*) NULL + 4 * sizeof (GLfloat) * i));
}
glBindBuffer(GL_ARRAY_BUFFER, 0);
for (GLint i = 0; i < size; ++i)
glEnableVertexAttribArray(m_attribLocations[i]);
if (m_useIndexBuffer) {
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_indexBufferId);
if (m_dynamicRendering) {
glDrawElements(m_primitiveMode, m_nrDynamicIndices, GL_UNSIGNED_INT, 0);
} else {
glDrawElements(m_primitiveMode, m_nrIndices, GL_UNSIGNED_INT, 0);
}
} else {
if (m_dynamicRendering) {
glDrawArrays(m_primitiveMode, 0, m_nrDynamicVertices);
} else {
glDrawArrays(m_primitiveMode, 0, m_nrVertices);
}
}
for (GLint i = 0; i < size; ++i)
glDisableVertexAttribArray(m_attribLocations[i]);
}
如果我将这段代码与教程中的步骤进行比较，我看不到任何错误或错误顺序。
请注意，我无法使用较新的GLSL版本，因为我目前的Linux版本仅支持1.3。
您不使用'sampler2D'对立方体贴图进行采样，而是使用'samplerCube'和3D纹理坐标来表示查找方向。我不确定你目前正在用2D坐标来做什么？ –
哦！非常感谢！我已经改变了片段着色器，现在它可以工作（纹理仍然是扭曲的，但是我认为我会自己去做）。 – pedjjj
这里工作片段着色器： '#version 130 in vec4 VertPosition; in vec4 VertNormal; in vec4 VertColor; in vec4 VertTexture; //顶点着色器的插值，类似于教程:-) uniform vec3 lightPos; uniform samplerCube skyBoxTextureSampler; //从教程中知道要访问哪个纹理:-) void main（） { vec4 color = VertColor; gl_FragColor = texture（skyBoxTextureSampler，VertTexture.xyz）; //看起来像纹理本身没有加载，因为这也会产生黑色的vec2（0.8f，0.2f））; // \t // vec4（1.0f，1.0f，0.9f，1.0f）; // }' – pedjjj