STB将png加载到OpenGl纹理会产生黑色或白色背景

Question

你好，我的代码有一个奇怪的问题，我在堆栈上找了一段时间，但没有找到答案，几乎没有类似的问题，但它们没有解决任何问题。

int createTexture(const char* path) {
unsigned int texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
int width, height, nrChannels;
unsigned char* data = stbi_load(path, &width, &height, &nrChannels, 0);
int colorMode = nrChannels == 3 ? GL_RGB : GL_RGBA;
if (data) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, colorMode, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
} else {
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data);
return texture;
}

这里我有函数加载纹理，我根据通道的数量选择GL_RGB或GL_RGBA。根据我使用的jpg/png图像，我有3个和4个通道的好结果。无论如何，我有白色背景，(在我在GIMP中编辑它之前是黑色的(

// set the texture wrapping/filtering options (on currently bound 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);


// load and create a texture 
// -------------------------
unsigned int texture1 = createTexture("brick.jpg");
unsigned int texture2 = createTexture("grafiti.png");
// Mode
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
// Shader Class
Shader currentShader("vertexShader.glsl", "fragmentShader.glsl");
currentShader.use();
currentShader.setInt("texture1", 0);
currentShader.setInt("texture2", 1);
while (!glfwWindowShouldClose(window)) {
processInput(window);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texture2);
currentShader.use();
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, sizeof(indices) / sizeof(int), GL_UNSIGNED_INT, 0);
glBindVertexArray(0);
glfwSwapBuffers(window);
glfwPollEvents();
}

然后我把这个纹理和这个着色器一起使用

碎片

#version 330 core
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
uniform sampler2D texture1;
uniform sampler2D texture2;
void main()
{
FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 1);
}

顶点

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aTexCoord;
out vec3 ourColor;
out vec2 TexCoord;
void main()
{
gl_Position = vec4(aPos, 1.0);
ourColor = aColor;
TexCoord = aTexCoord;
}
float vertices[] = {
// positions // colors // texture coords
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left
};
unsigned int indices[] = {
0, 1, 3,
1, 2, 3,
};
unsigned int VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

unsigned int VAO;
glGenVertexArrays(1, &VAO);
glBindVertexArray(VAO);
unsigned int EBO;
glGenBuffers(1, &EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);

如果我的英语很糟糕，我很抱歉，但现在是半夜，我已经为此挣扎了好几个小时了

Answer 1

我找到了解决方案，启用混合并不令人满意，所以我用不同的方式编写了fragmentShader

#version 330 core
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
uniform sampler2D texture1;
uniform sampler2D texture2;
void main()
{
vec4 AlphaColor = texture(texture2, TexCoord);
if(AlphaColor.a < 0.1) {
FragColor = texture(texture1, TexCoord);
} else {
FragColor = mix(texture(texture1, TexCoord), AlphaColor, 0.9);
}
}

现在FragmentShader了解alpha通道，将只混合没有alpha 的像素