如何将多个纹理传递给单个着色器？

Question

uniform sampler2D DecalTex; //The texture
uniform sampler2D BumpTex; //The bump-map 

他们没有提到的是如何首先将两个纹理传递给着色器。

以前我

//OpenGL cpp file
glBindTexture(GL_TEXTURE_2D, textureHandle);

//Vertex shader
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;

//Fragment shader
gl_FragColor = color * texture2D(DecalTex,gl_TexCoord[0].xy);

所以现在我

//OpenGL cpp file
glBindTexture(GL_TEXTURE_2D, textureHandle);
glBindTexture(GL_TEXTURE_2D, bumpHandle);

//Vertex shader
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
gl_TexCoord[1] = gl_TextureMatrix[1] * gl_MultiTexCoord1;

//Fragment shader
gl_FragColor = color * texture2D(BumpTex,gl_TexCoord[0].xy);
//no bump logic yet, just testing I can use texture 1 instead of texture 0

• 如何将大小不同的纹理数组传递给GLSL？
• 将多个纹理从OpenGL传递到GLSL着色器
• GLSL中的多个纹理-只有一个有效

（这是家庭作业，所以请用最少的代码片段回答（如果有的话）。谢谢！）

如果做不到这一点，有人有茶具吗？

Answer 1

很简单，真的。您所需要的就是使用gluniform1i将采样器绑定到某个纹理单元。所以对于您的代码示例，假设有两个统一的采样器：

uniform sampler2D DecalTex;  // The texture  (we'll bind to texture unit 0)
uniform sampler2D BumpTex;   // The bump-map (we'll bind to texture unit 1)

在初始化代码中：

// Get the uniform variables location. You've probably already done that before...
decalTexLocation = glGetUniformLocation(shader_program, "DecalTex");
bumpTexLocation  = glGetUniformLocation(shader_program, "BumpTex");

// Then bind the uniform samplers to texture units:
glUseProgram(shader_program);
glUniform1i(decalTexLocation, 0);
glUniform1i(bumpTexLocation,  1);

好的，着色器制服设置，现在我们渲染。为此，您将需要通常的glbindtexture和glactivetexture:

glActiveTexture(GL_TEXTURE0 + 0); // Texture unit 0
glBindTexture(GL_TEXTURE_2D, decalTexHandle);

glActiveTexture(GL_TEXTURE0 + 1); // Texture unit 1
glBindTexture(GL_TEXTURE_2D, bumpHandle);

// Done! Now you render normally.

vec4 a = texture2D(DecalTex, tc);
vec4 b = texture2D(BumpTex,  tc);