[英]Getting textures to work in OpenGL 3.2
我一直盯着这段代码已经有一段时间了,没有运气。 我正在将librocket集成到我自己的项目中(该库对问题不是那么重要),其中一部分需要编写renderer类。 我一直试图做到这一点,但无法显示纹理。 顶点颜色和位置可以正常工作。
我正在使用OpenGL3.2。
我临时修改了代码以尝试绘制单个四边形。 使用的唯一参数是texture
参数,它只是将GLuint
为另一种类型。
我很可能会丢失一些愚蠢的东西,但我看不到。 希望另一双眼睛会有所帮助。 随时要求更多代码/信息。
// Called by Rocket when it wants to render geometry that it does not wish to optimise.
void SDLRenderInterface::RenderGeometry(Rocket::Core::Vertex* vertices, int num_vertices, int* indices, int num_indices, const Rocket::Core::TextureHandle texture, const Rocket::Core::Vector2f& translation)
{
GLuint program;
GLuint vertexBuffer;
GLuint indexBuffer;
GLuint vertexPosLoc = 0;
GLuint vertexColorLoc = 0;
GLuint vertexTexCoordLoc = 0;
GLuint texSamplerLoc = 0;
GLuint translationLoc = 0;
GLuint viewDimLoc = 0;
int offset = 8;
int vertexCount = 4;
float vertexData[] = {-0.5, -0.5, 1.0, 1.0, 1.0, 1.0, 0.0, 0.0,
0.5, -0.5, 1.0, 1.0, 1.0, 1.0, 1.0, 0.0,
0.5, 0.5, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0,
-0.5, 0.5, 1.0, 1.0, 1.0, 1.0, 0.0, 1.0};
int indexData[] = {0,1,2,0,2,3};
int indexCount = 6;
// Populate vertex buffer
glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(float)*offset*vertexCount,
vertexData, GL_STATIC_DRAW);
// Populate index buffer
glGenBuffers(1, &indexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(int) * indexCount,
indexData, GL_STATIC_DRAW);
program = shaderManager->getProgram(2, "rocketTex.vert",
"rocketTex.frag");
glUseProgram(program);
// Set up the texture
texSamplerLoc = glGetUniformLocation(program, "texSampler");
vertexTexCoordLoc = glGetAttribLocation(program, "vertexTexCoord");
if(texSamplerLoc == -1)
{
std::cerr << "Error: cannot find texture location." << std::endl;
return;
}
if(vertexTexCoordLoc == -1)
{
std::cerr << "Error: cannot find texture coord location."
<< std::endl;
return;
}
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, (GLuint) texture);
glUniform1i(texSamplerLoc, 0);
// Set up the per vertex texture coords
glEnableVertexAttribArray(vertexTexCoordLoc);
glVertexAttribPointer(vertexTexCoordLoc, 2, GL_FLOAT, GL_FALSE,
offset * sizeof(float),
(void*) (sizeof(float) * 6));
// Set up uniforms
translationLoc = glGetUniformLocation(program, "translation");
viewDimLoc = glGetUniformLocation(program, "viewDimensions");
if(translationLoc == -1)
{
std::cerr << "Error: cannot find translation location."
<< std::endl;
return;
}
if(viewDimLoc == -1)
{
std::cerr << "Error: cannot find viewDim location."
<< std::endl;
return;
}
glUniform2f(translationLoc, 0,0);
glUniform2f(viewDimLoc, 1,1);
// Set up per-vertex attributes
vertexPosLoc = glGetAttribLocation(program, "vertexPosition");
vertexColorLoc = glGetAttribLocation(program, "vertexColor");
if(vertexPosLoc == -1)
{
std::cerr << "Error: cannot find vertex position location."
<< std::endl;
return;
}
if(vertexColorLoc == -1)
{
std::cerr << "Error: cannot find vertex color location."
<< std::endl;
return;
}
glEnableVertexAttribArray(vertexPosLoc);
glEnableVertexAttribArray(vertexColorLoc);
glVertexAttribPointer(vertexPosLoc, 2, GL_FLOAT, GL_FALSE,
offset * sizeof(float), 0);
glVertexAttribPointer(vertexColorLoc, 4, GL_FLOAT, GL_TRUE,
offset * sizeof(float),
(void*) (sizeof(float) * 2));
// Draw the geometry
glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_INT, 0);
glDisableVertexAttribArray(vertexPosLoc);
glDisableVertexAttribArray(vertexColorLoc);
glDisableVertexAttribArray(vertexTexCoordLoc);
glDeleteBuffers(1, &vertexBuffer);
glDeleteBuffers(1, &indexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glUseProgram(0);
}
顶点着色器:
#version 120
uniform vec2 translation;
uniform vec2 viewDimensions;
attribute vec2 vertexPosition;
attribute vec4 vertexColor;
attribute vec2 vertexTexCoord;
varying vec2 texCoord;
varying vec4 fragColor;
void main(void)
{
vec2 ndcPos = ((vertexPosition + translation)/(viewDimensions));
texCoord = vertexTexCoord;
fragColor = vertexColor;
gl_Position = vec4(ndcPos, 0.0, 1.0);
}
片段着色器:
#version 120
uniform sampler2D texSampler;
varying vec2 texCoord;
varying vec4 fragColor;
void main(void)
{
vec4 objectColor = texture2D(texSampler, texCoord);
gl_FragColor = vec4((objectColor * fragColor).xyz, 1.0);
}
所以,我终于想通了。 jozxyqk关于测试纹理坐标的建议证实了我的怀疑,即纹理坐标已关闭(每个顶点都获得相同的坐标)。 问题最终导致我在代码的另一部分中调用glVertexAttribDivisor(attributeLoc, 1)
,并且从未将其设置回每个顶点,因此影响了我的其他着色器。 考虑到OpenGL的设计,这很有必要。
很高兴解决了!
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