当我尝试对纹理进行采样时 GLSL 着色器变黑

Question

我用这种方式渲染了一个三角形带，使用基本的旁路着色器一切正常：编辑：我添加了 TextCoords 并修改了着色器，我一直得到相同的结果，我的 3d 对象变黑了！

更新代码：

// Dibuixem tots els prismes
    glBegin(GL_TRIANGLE_STRIP);
    for(i=0;i<num_elems;i++) {
        for(j=0;j<num_vertices;j++) {

            glNormal3fv((GLfloat *)(a+j*2));
            glTexCoord2f(0.0f, 0.0f); 
            glVertex3fv((GLfloat *)(a+j*2+1));
            glTexCoord2f(1.0f, 0.0f); 
            glNormal3fv((GLfloat *)(b+j*2));
            glTexCoord2f(1.0f, 1.0f); 
            glVertex3fv((GLfloat *)(b+j*2+1));
        }

        glNormal3fv((GLfloat *)(a));
        glTexCoord2f(0.0f, 1.0f);
        glVertex3fv((GLfloat *)(a+1));
        glNormal3fv((GLfloat *)(b));
        glTexCoord2f(0.0f, 0.0f); 
        glVertex3fv((GLfloat *)(b+1));
        a+=face_size;
        b+=face_size;
    }
    glEnd();

我正在尝试将纹理附加到我的着色器，但我不知道如何传递纹理。

我以这种方式创建纹理并将其添加到我的程序中。纹理数据已验证格式为 unsigned char data[imageSize];:

的数组

   GLuint textureID;
   glGenTextures(1, &textureID);
   glBindTexture(GL_TEXTURE_2D, textureID);
   glActiveTexture(GL_TEXTURE0); // Texture unit 0
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
   glTexImage2D(GL_TEXTURE_2D, 0,GL_BGR, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);

这是我在另一篇有相同问题的帖子中读到的，我在编译我的着色器并无误地生成我的程序后添加到我的代码中。教程倾向于忽略此信息（您如何向着色器说明绑定纹理的名称和位置）。

GLuint t1Location = glGetUniformLocation(programID, "tex1");
glUniform1i(t1Location, 0);

还有我的着色器 更新代码:

#define GLSL(version, shader) "#version " #version "\n" #shader
const char* vert = GLSL
(
    110,

    varying vec4 position;
    varying vec3 normal;
    varying out vec4 texCoord;
    varying vec2 coord;
    void main()
    {
        position    = gl_ModelViewMatrix * gl_Vertex;
        normal      = normalize( gl_NormalMatrix * gl_Normal.xyz );
        gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
        coord       = vec2(gl_MultiTexCoord0);
    } 
);


    


const char* frag  = GLSL
(
    110,
        
    uniform sampler2D tex1;
    varying vec4 position;
    varying vec3 normal;
    varying vec2 coord;
    
    void main()
    {
         gl_FragColor = texture2D(tex1, coord);
    } 
);

编辑 2：

我是这样设置 gl 的：（也许某些东西与我的纹理着色器冲突，但我不这么认为！

 /* set up depth-buffering */
   glEnable(GL_DEPTH_TEST);

   glEnable(GL_POLYGON_SMOOTH);
   glHint(GL_POLYGON_SMOOTH_HINT, GL_FASTEST);

   /* set up lights */
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();

   glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
   glShadeModel(GL_SMOOTH);

   GLfloat lightpos[]   = { 3.0, 0.0, 1.0, 0.0 };
   GLfloat lightcolor[] = { 0.5, 0.5, 0.5, 1.0 };
   GLfloat ambcolor[]   = { 0.5, 0.5, 0.5, 1.0 };

   glLightModelfv(GL_LIGHT_MODEL_AMBIENT,ambcolor);

   glEnable(GL_LIGHTING);
   glColorMaterial(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE);

   glEnable  (GL_COLOR_MATERIAL);
   glLightfv (GL_LIGHT0,GL_POSITION,lightpos);
   glLightfv (GL_LIGHT0,GL_AMBIENT,ambcolor);
   glLightfv (GL_LIGHT0,GL_DIFFUSE,lightcolor);
   glLightfv (GL_LIGHT0,GL_SPECULAR,lightcolor);
   glLightf  (GL_LIGHT0,GL_CONSTANT_ATTENUATION,0.2);
   glLightf  (GL_LIGHT0,GL_LINEAR_ATTENUATION,0.0);
   glLightf  (GL_LIGHT0,GL_QUADRATIC_ATTENUATION,1.0);
   glEnable  (GL_LIGHT0);
   glEnable(GL_TEXTURE_2D);

用纯色替换 gl_FragColor 效果很好。我知道可能与 coord 参数有关，但我正在尝试我发现的所有东西，但没有任何东西适合我。

Answer 1

内部纹理格式GL_BGR无效。 GL_BGR 对源纹理的格式有效，但内部表示必须是 GL_RGB.
参见 glTexImage2D。

像这样调整您的代码：

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);

请参阅 Khronos 参考页 GLAPI/glTexImage2D，上面写着：

To define texture images, call glTexImage2D. The arguments describe the parameters of the texture image, such as height, width, width of the border, level-of-detail number (see glTexParameter), and number of color components provided. The last three arguments describe how the image is represented in memory.

format determines the composition of each element in data. It can assume one of these symbolic values:

GL_BGR: Each element is an RGB triple. The GL converts it to floating point and assembles it into an RGBA element by attaching 1 for alpha. Each component is clamped to the range [0,1].

当我尝试对纹理进行采样时 GLSL 着色器变黑

GLSL Shader going black when I try to sample a texture

c

opengl

shader

glsl

texture-mapping