[英]OpenGL showing stripes when using sampler2D
尝试在 C++ 中编写 OpenGL 应用程序时遇到了一个奇怪的问题。 减少代码后,我发现问题出在纹理采样上。 在纹理之上有奇怪的条纹:
奇怪的是,当我调整 window 的大小时,条纹的粗细也发生了变化:
我不认为着色器有什么问题,但它们是:
//-----------------Vertex-----------------
#version 330 core
layout (location = 0) in vec3 pos_;
layout (location = 1) in vec3 color_;
layout (location = 2) in vec2 uv_;
out vec2 uv;
void main()
{
uv = uv_;
gl_Position = vec4(pos_, 1.0);
}
//-----------------Fragment---------------
#version 330 core
out vec4 frag_color;
in vec2 uv;
uniform sampler2D diffuse_;
void main()
{
frag_color = texture(diffuse_, uv);
}
我也认为这可能不是纹理加载问题的原因,但不管它是:
GLuint load_texture(const std::string& source)
{
GLuint texture = 0;
int width, height, nrChannels;
unsigned char* data = stbi_load(source.c_str(), &width, &height, &nrChannels, 0);
if (data != nullptr)
{
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cerr << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
return texture;
}
另外,如果有帮助,这里我提供分配顶点属性的代码:
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(0 * sizeof(GLfloat)));
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(3 * sizeof(GLfloat)));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(6 * sizeof(GLfloat)));
glEnableVertexAttribArray(2);
并设置纹理统一:
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, diffuse);
glUseProgram(shader);
glUniform1i(glGetUniformLocation(shader, "diffuse_"), 0);
对不起,如果那是很多代码,但我不知道问题出在哪里。 你们有没有人以前见过这样的事情并且知道如何解决这个问题?
感谢@Botje,问题得以解决。 使用glTexImage2D
给OpenGL的通道数量不等于nrChannels
。 我可以通过在load_texture
内进行简单的switch
来解决此load_texture
。 这是更新的版本:
GLuint load_texture(const std::string& source)
{
GLuint texture = 0;
int width, height, nrChannels;
unsigned char* data = stbi_load(source.c_str(), &width, &height, &nrChannels, 0);
if (data != nullptr)
{
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
GLenum format;
switch (nrChannels)
{
case 1:
format = GL_LUMINANCE;
break;
case 2:
format = GL_LUMINANCE_ALPHA;
break;
case 3:
format = GL_RGB;
break;
case 4:
format = GL_RGBA;
break;
}
glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cerr << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
return texture;
}
加载 jpg 图像时我遇到了同样的问题。设置 GL_UNPACK_ALIGNMENT 修复了它。 https://github.com/nothings/stb/issues/695
if (channels == 3) {
//HERE WAS THE MISTAKE
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
}
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