Question

我们无法在open gl中添加纹理。

这里我们的代码用于制作简单的黑/白案例纹理：

 GLuint tex;//before the main function

然后在主要：

glGenTextures(1, &tex);

float pixels[] = {
    0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
    1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f
};
glBindTexture(GL_TEXTURE_2D, tex);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0, GL_RGB, GL_FLOAT, pixels);
glEnable(GL_TEXTURE_2D);

然后在draw方法中我们以下列方式应用它

glBegin(GL_QUADS);
    glTexCoord2d(0, 1);     glVertex3d(0, -0.1, 0);
    glTexCoord2d(0, 0);     glVertex3d(50, -0.1, 0);
    glTexCoord2d(1, 1);     glVertex3d(50, -0.1, 50);
    glTexCoord2d(1, 1);     glVertex3d(0, -0.1, 50);
glEnd();

我们希望在场景的基础上简单地应用这种纹理。我们错过了什么吗？

Answer 1

Upload a complete set of mipmaps or set GL_TEXTURE_MIN_FILTER to GL_NEAREST or GL_LINEAR
Set GL_TEXTURE_ENV_MODE改为GL_DECAL而非默认GL_MODULATE或glColor3ub(255, 255, 255)。

所有在一起：

// http://glew.sourceforge.net/
#include <GL/glew.h>

#include <GL/glut.h>

GLuint tex = 0;
void init()
{
    // upload texture
    glGenTextures( 1, &tex );
    glBindTexture( GL_TEXTURE_2D, tex );
    float pixels[] =
    {
        1, 0, 0,    0, 1, 0,
        0, 0, 1,    1, 1, 1,
    };
    glTexImage2D
        (
        GL_TEXTURE_2D, 0, 
        GL_RGB, 2, 2, 0,
        GL_RGB, GL_FLOAT, pixels
        );

    // configure texture unit
    glActiveTexture( GL_TEXTURE0 + 0 );
    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
}

void display()
{
    glClearColor( 0, 0, 0, 1 );
    glClear(GL_COLOR_BUFFER_BIT);

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    glOrtho( -2, 2, -2, 2, -1, 1 );

    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();

    // select texture unit & enable it
    glActiveTexture( GL_TEXTURE0 + 0 );
    glEnable( GL_TEXTURE_2D );

    glBindTexture( GL_TEXTURE_2D, tex );
    glBegin(GL_QUADS);
        glTexCoord2i( 0, 0 );     glVertex2i( -1, -1 );
        glTexCoord2i( 1, 0 );     glVertex2i(  1, -1 );
        glTexCoord2i( 1, 1 );     glVertex2i(  1,  1 );
        glTexCoord2i( 0, 1 );     glVertex2i( -1,  1 );
    glEnd();

    glutSwapBuffers();
}

int main( int argc, char** argv )
{
    glutInit( &argc, argv );
    glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
    glutCreateWindow( "GLUT" );
    glewInit();
    glutDisplayFunc( display );
    init();
    glutMainLoop();
    return 0;
}

在open gl中加载纹理

1 个答案: