GLSL中的多个纹理-只有一个可用

下面是一个基本的GLUT示例(写在OSX上,根据需要进行调整),它生成两个棋盘纹理,加载一个带有两个采样器的着色器,并通过着色(一个红色,一个蓝色)和混合来组合它们。看看这是否适合你:

#include <stdio.h>
#include <stdlib.h>

#include <GLUT/glut.h>
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>

#define kTextureDim 64

GLuint t1;
GLuint t2;

/* adapted from the red book */
GLuint makeCheckTex() {
    GLubyte image[kTextureDim][kTextureDim][4]; // RGBA storage

    for (int i = 0; i < kTextureDim; i++) {
        for (int j = 0; j < kTextureDim; j++) {
            int c = ((((i & 0x8) == 0) ^ ((j & 0x8)) == 0))*255;
            image[i][j][0]  = (GLubyte)c;
            image[i][j][1]  = (GLubyte)c;
            image[i][j][2]  = (GLubyte)c;
            image[i][j][3]  = (GLubyte)255;
        }
    }

    GLuint texName;
    glGenTextures(1, &texName);    
    glBindTexture(GL_TEXTURE_2D, texName);
    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_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kTextureDim, kTextureDim, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);

    return texName;
}

void loadShader() {
#define STRINGIFY(A) #A

    const GLchar* source = STRINGIFY(

                                     uniform sampler2D tex1;
                                     uniform sampler2D tex2;

                                     void main() {
                                         vec4 s1 = texture2D(tex1, gl_TexCoord[0].st);
                                         vec4 s2 = texture2D(tex2, gl_TexCoord[0].st + vec2(0.0625, 0.0625));
                                         gl_FragColor = mix(vec4(1, s1.g, s1.b, 0.5), vec4(s2.r, s2.g, 1, 0.5), 0.5);
                                     }

                                     );

    GLuint program = glCreateProgram();
    GLuint shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(shader, 1, &source, NULL);
    glCompileShader(shader);

    GLint logLength;
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLength);
    if (logLength > 0) {
        GLchar* log = (GLchar*)malloc(logLength);
        glGetShaderInfoLog(shader, logLength, &logLength, log);
        printf("Shader compile log:\n%s\n", log);
        free(log);
    }

    glAttachShader(program, shader);  
    glLinkProgram(program);

    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &logLength);
    if (logLength > 0) {
        GLchar* log = (GLchar*)malloc(logLength);
        glGetProgramInfoLog(program, logLength, &logLength, log);
        printf("Program link log:\n%s\n", log);
        free(log);
    }

    GLuint t1Location = glGetUniformLocation(program, "tex1");
    GLuint t2Location = glGetUniformLocation(program, "tex2");

    glUniform1i(t1Location, 0);
    glUniform1i(t2Location, 1);

    glUseProgram(program);
}


void init()
{
    glClearColor(0.0, 0.0, 0.0, 0.0);
    glEnable(GL_DEPTH_TEST);
    glShadeModel(GL_FLAT);

    t1 = makeCheckTex();
    t2 = makeCheckTex();

    loadShader();
}


void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();

    glActiveTexture(GL_TEXTURE0);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, t1);

    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, t2);

    glBegin(GL_QUADS);
    //lower left
    glTexCoord2f(0, 0);
    glVertex2f(-1.0, -1.0);
    //upper left
    glTexCoord2f(0, 1.0);
    glVertex2f(-1.0, 1.0);
    //upper right
    glTexCoord2f(1.0, 1.0);
    glVertex2f(1.0, 1.0);
    //lower right
    glTexCoord2f(1.0, 0);
    glVertex2f(1.0, -1.0);
    glEnd();

    glutSwapBuffers();
}


void reshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-2, 2, -2, 2, -2, 2);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}


int main(int argc, char **argv)
{
    glutInit(&argc, argv);

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_DEPTH | GLUT_RGBA);

    glutInitWindowSize(512, 512);
    glutInitWindowPosition(0, 0);

    glutCreateWindow("GLSL Texture Blending");

    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutIdleFunc(display);

    init();

    glutMainLoop();
    return 0;
}

希望结果会像这样(你可以注释掉 glUseProgram 调用以查看在没有着色器的情况下绘制的第一个纹理):

只是为了帮助其他人谁可能有兴趣使用多种纹理,并会觉得无望后,天搜索一个答案。我发现你需要打电话

glUseProgram(program);

GLuint t1Location = glGetUniformLocation(program, "tex1");
GLuint t2Location = glGetUniformLocation(program, "tex2");

glUniform1i(t1Location, 0);
glUniform1i(t2Location, 1);

很晚才回复,但对于任何遇到这种情况的人来说——我也遇到了同样的问题,经过短暂的调整后,我意识到 glActiveTexture(GL_TEXTURE0) 解决了这个问题。 如果活动纹理单元没有被“重置”为零,那么接下来的事情似乎会变得混乱。 能够

编译着色器进行测试时,我发现两个错误:

1. coords 应分配 st 四分量部分 gl_TexCoord ,例如。

   vec2 coords = gl_TexCoord[0].st;
   

2. 着色器不应以分号结尾。

你在主程序的任何地方检查着色器编译是否正确吗?你可以看看 GL_COMPILE_STATUS 通过 glGetShader 和 glGetShaderInfoLog .

glActiveTexture 呼叫不起作用。是否确定已正确设置函数指针?

通过调用验证 glGetIntegerv(GL_ACTIVE_TEXTURE, &anint) 在调用了glActiveTexture(GL\u TEXTURE1)之后。

阿尔索 glEnable(GL_TEXTURE_2D) 都没用。着色器本身指定要使用的纹理单元,以及每个单元中要“启用”的目标。

编辑以添加:

嗯,你的新情况很特别。事实上,你甚至不能显示红色是奇怪的,特别是(好吧,你设置阿尔法为1只是为了确保?)。

玻璃结构 设置完纹理单元1后(即 glBindTexture 电话)。