我只是想将图像作为纹理映射到立方体的表面并显示。立方体上没有我的图像，而是完全黑色的。我的图像都是 64x64 jpg 的。
我的应用程序代码如下。最初它是一个生成 2 个棋盘纹理的程序，在立方体的所有面上一次显示 1 个，允许用户在它们之间切换。我想要一个图像，而不是所有面孔上的棋盘格。我已经注释掉了他们的纹理生成和纹理加载代码，最重要的是用 ilutGLLoadImage()（来自 DevIL）替换它：它应该用一块石头杀死大多数加载图像纹理的鸟。这发生在 init() 中。唯一的控制台输出是“1,2”（来自我的 cout），这意味着图像已加载并提供了有效的纹理 ID。为什么立方体是黑色的？
应用程序代码（init() 是一个很好的起点）：
#include "Angel.h"
#include <IL\config.h>
#include <IL\ilut_config.h>
#include <IL\il.h>
#include <IL\ilu.h>
#include <IL\ilut.h>
#include <iostream>
using namespace std;
const int NumTriangles = 12; // (6 faces)(2 triangles/face)
const int NumVertices = 3 * NumTriangles;
const int TextureSize = 64;
typedef Angel::vec4 point4;
typedef Angel::vec4 color4;
// Texture objects and storage for texture image
//GLuint textures[2];
GLuint tex1;
GLuint tex2;
//GLubyte image[TextureSize][TextureSize][3];
//GLubyte image2[TextureSize][TextureSize][3];
// Vertex data arrays
point4 points[NumVertices];
//color4 quad_colors[NumVertices];
vec2 tex_coords[NumVertices];
// Array of rotation angles (in degrees) for each coordinate axis
enum { Xaxis = 0, Yaxis = 1, Zaxis = 2, NumAxes = 3 };
int Axis = Xaxis;
GLfloat Theta[NumAxes] = { 0.0, 0.0, 0.0 };
GLuint theta;
//----------------------------------------------------------------------------
int Index = 0;
void
quad( int a, int b, int c, int d )
{
point4 vertices[8] = {
point4( -0.5, -0.5, 0.5, 1.0 ),
point4( -0.5, 0.5, 0.5, 1.0 ),
point4( 0.5, 0.5, 0.5, 1.0 ),
point4( 0.5, -0.5, 0.5, 1.0 ),
point4( -0.5, -0.5, -0.5, 1.0 ),
point4( -0.5, 0.5, -0.5, 1.0 ),
point4( 0.5, 0.5, -0.5, 1.0 ),
point4( 0.5, -0.5, -0.5, 1.0 )
};
color4 colors[8] = {
color4( 0.0, 0.0, 0.0, 1.0 ), // black
color4( 1.0, 0.0, 0.0, 1.0 ), // red
color4( 1.0, 1.0, 0.0, 1.0 ), // yellow
color4( 0.0, 1.0, 0.0, 1.0 ), // green
color4( 0.0, 0.0, 1.0, 1.0 ), // blue
color4( 1.0, 0.0, 1.0, 1.0 ), // magenta
color4( 0.0, 1.0, 1.0, 1.0 ), // white
color4( 1.0, 1.0, 1.0, 1.0 ) // cyan
};
// bottom-left texture coord
// quad_colors[Index] = colors[a];
points[Index] = vertices[a];
tex_coords[Index] = vec2( 0.0, 0.0 );
Index++;
// top-left texture coord
// quad_colors[Index] = colors[a];
points[Index] = vertices[b];
tex_coords[Index] = vec2( 0.0, 1.0 );
Index++;
// top-right
// quad_colors[Index] = colors[a];
points[Index] = vertices[c];
tex_coords[Index] = vec2( 1.0, 1.0 );
Index++;
// bottom-left
// quad_colors[Index] = colors[a];
points[Index] = vertices[a];
tex_coords[Index] = vec2( 0.0, 0.0 );
Index++;
// top-right
// quad_colors[Index] = colors[a];
points[Index] = vertices[c];
tex_coords[Index] = vec2( 1.0, 1.0 );
Index++;
// bottom-right
// quad_colors[Index] = colors[a];
points[Index] = vertices[d];
tex_coords[Index] = vec2( 1.0, 0.0 );
Index++;
}
//----------------------------------------------------------------------------
void
colorcube()
{
quad( 1, 0, 3, 2 );
quad( 2, 3, 7, 6 );
quad( 3, 0, 4, 7 );
quad( 6, 5, 1, 2 );
quad( 4, 5, 6, 7 );
quad( 5, 4, 0, 1 );
}
//----------------------------------------------------------------------------
void
init()
{
colorcube();
ILuint devilError;
ilInit();
iluInit();
ilutInit();
devilError = ilGetError();
if (devilError != IL_NO_ERROR) {
printf ("Devil Error (ilInit: %s\n", iluErrorString(devilError));
exit (2);
}
ilutRenderer(ILUT_OPENGL);
GLuint openglID, openglError;
tex1 = ilutGLLoadImage("test1.jpg");
tex2 = ilutGLLoadImage("test2.jpg");
cout << tex1 << "," << tex2 << endl;
devilError = ilGetError();
if (devilError != IL_NO_ERROR) {
printf ("Error: %s\n", iluGetString (devilError));
exit (2);
}
if (openglError != GL_NO_ERROR) {
printf ("Opengl Error (ilutGLBindTexImage): %s\n", gluGetString (openglError));
exit (2);
}
// // Create a checkerboard pattern
// for ( int i = 0; i < 64; i++ ) {
// for ( int j = 0; j < 64; j++ ) {
// GLubyte c = (((i & 0x8) == 0) ^ ((j & 0x8) == 0)) * 255;
// image[i][j][0] = c;
// image[i][j][1] = c;
// image[i][j][2] = c;
// image2[i][j][0] = c;
// image2[i][j][1] = 0;
// image2[i][j][2] = c;
// }
// }
//
// // Initialize texture objects
//
// // Get unused texture identifiers
// glGenTextures( 2, textures );
//
glBindTexture( GL_TEXTURE_2D, tex1 );
//
// // Specify that 'image' is to be used as a two-dimensional texture
// glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, TextureSize, TextureSize, 0,
// GL_RGB, GL_UNSIGNED_BYTE, image );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST );
// glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
//
glBindTexture( GL_TEXTURE_2D, tex2 );
// glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, TextureSize, TextureSize, 0,
// GL_RGB, GL_UNSIGNED_BYTE, image2 );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST );
// glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glActiveTexture( GL_TEXTURE0 );
// Set the current texture object
glBindTexture( GL_TEXTURE_2D, tex1 );
// Create a vertex array object
GLuint vao;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
// Create and initialize a buffer object
GLuint buffer;
glGenBuffers( 1, &buffer );
glBindBuffer( GL_ARRAY_BUFFER, buffer );
// glBufferData( GL_ARRAY_BUFFER,
// sizeof(points) + sizeof(quad_colors) + sizeof(tex_coords),
// NULL, GL_STATIC_DRAW );
glBufferData( GL_ARRAY_BUFFER,
sizeof(points) + sizeof(tex_coords),
NULL, GL_STATIC_DRAW );
// Specify an offset to keep track of where we're placing data in our
// vertex array buffer. We'll use the same technique when we
// associate the offsets with vertex attribute pointers.
GLintptr offset = 0;
glBufferSubData( GL_ARRAY_BUFFER, offset, sizeof(points), points );
offset += sizeof(points);
// glBufferSubData( GL_ARRAY_BUFFER, offset,
// sizeof(quad_colors), quad_colors );
// offset += sizeof(quad_colors);
glBufferSubData( GL_ARRAY_BUFFER, offset, sizeof(tex_coords), tex_coords );
// Load shaders and use the resulting shader program
GLuint program = InitShader( "vshader71.glsl", "fshader71.glsl" );
glUseProgram( program );
// set up vertex arrays
offset = 0;
GLuint vPosition = glGetAttribLocation( program, "vPosition" );
glEnableVertexAttribArray( vPosition );
glVertexAttribPointer( vPosition, 4, GL_FLOAT, GL_FALSE, 0,
BUFFER_OFFSET(offset) );
offset += sizeof(points);
// GLuint vColor = glGetAttribLocation( program, "vColor" );
// glEnableVertexAttribArray( vColor );
// glVertexAttribPointer( vColor, 4, GL_FLOAT, GL_FALSE, 0,
// BUFFER_OFFSET(offset) );
// offset += sizeof(quad_colors);
// Pass the texture coordinates as a vertex attribute with the identifier 'vTextCoord'
GLuint vTexCoord = glGetAttribLocation( program, "vTexCoord" );
glEnableVertexAttribArray( vTexCoord );
glVertexAttribPointer( vTexCoord, 2, GL_FLOAT, GL_FALSE, 0,
BUFFER_OFFSET(offset) );
// Set the value of the fragment shader texture sampler variable
// ("texture") to the the appropriate texture unit. In this case,
// zero, for GL_TEXTURE0 which was previously set by calling
// glActiveTexture().
glUniform1i( glGetUniformLocation(program, "texture"), 0 );
theta = glGetUniformLocation( program, "theta" );
glEnable( GL_DEPTH_TEST );
glClearColor( 1.0, 1.0, 1.0, 1.0 );
}
void
display( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glUniform3fv( theta, 1, Theta );
glDrawArrays( GL_TRIANGLES, 0, NumVertices );
glutSwapBuffers();
}
//----------------------------------------------------------------------------
void
mouse( int button, int state, int x, int y )
{
if ( state == GLUT_DOWN ) {
switch( button ) {
case GLUT_LEFT_BUTTON: Axis = Xaxis; break;
case GLUT_MIDDLE_BUTTON: Axis = Yaxis; break;
case GLUT_RIGHT_BUTTON: Axis = Zaxis; break;
}
}
}
//----------------------------------------------------------------------------
void
idle( void )
{
Theta[Axis] += 0.01;
if ( Theta[Axis] > 360.0 ) {
Theta[Axis] -= 360.0;
}
glutPostRedisplay();
}
//----------------------------------------------------------------------------
void
keyboard( unsigned char key, int mousex, int mousey )
{
switch( key ) {
case 033: // Escape Key
case 'q': case 'Q':
exit( EXIT_SUCCESS );
break;
case '1':
glBindTexture( GL_TEXTURE_2D, tex1 );
break;
case '2':
glBindTexture( GL_TEXTURE_2D, tex2 );
break;
}
glutPostRedisplay();
}
//----------------------------------------------------------------------------
int
main( int argc, char **argv )
{
glutInit( &argc, argv );
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
glutInitWindowSize( 512, 512 );
glutInitContextVersion( 3, 2 );
glutInitContextProfile( GLUT_CORE_PROFILE );
glutCreateWindow( "Texture Cube" );
glewExperimental = GL_TRUE;
glewInit();
init();
glutDisplayFunc( display );
glutKeyboardFunc( keyboard );
glutMouseFunc( mouse );
glutIdleFunc( idle );
glutMainLoop();
return 0;
}
顶点着色器：
#version 150
in vec4 vPosition;
in vec2 vTexCoord;
out vec4 color;
out vec2 texCoord;
uniform vec3 theta;
void main()
{
const float DegreesToRadians = 3.14159265 / 180.0;
vec3 c = cos( DegreesToRadians * theta );
vec3 s = sin( DegreesToRadians * theta );
mat4 rx = mat4( 1.0, 0.0, 0.0, 0.0,
0.0, c.x, -s.x, 0.0,
0.0, s.x, c.x, 0.0,
0.0, 0.0, 0.0, 1.0);
mat4 ry = mat4( c.y, 0.0, s.y, 0.0,
0.0, 1.0, 0.0, 0.0,
-s.y, 0.0, c.y, 0.0,
0.0, 0.0, 0.0, 1.0 );
// Workaround for bug in ATI driver
ry[1][0] = 0.0;
ry[1][1] = 1.0;
mat4 rz = mat4( c.z, -s.z, 0.0, 0.0,
s.z, c.z, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0,
0.0, 0.0, 0.0, 1.0 );
// Workaround for bug in ATI driver
rz[2][2] = 1.0;
texCoord = vTexCoord;
gl_Position = rz * ry * rx * vPosition;
}
片段着色器：
#version 150
in vec2 texCoord;
out vec4 fColor;
uniform sampler2D texture;
void main()
{
fColor = texture2D( texture, texCoord );
}