Question

我正在尝试根据this code进行一些体积渲染。

我现在正在做的是我有一些示例3D数据（数组chBuffer本质上是一个4 * 4 * 4测试数据阵列），我正在将其转换为OpenGL 3D纹理。之后，我试图使用其他OpenGL命令渲染此纹理。但是，当我运行应用程序时，屏幕显示为完全黑色。是否有任何具体问题应该解决这个问题？

这是我的代码：

#include <glut.h>
#include <GL/gl.h>
#include <gl/glext.h>
#include <stdio.h>
#include <Windows.h>
GLfloat dOrthoSize = 1.0f;
GLuint mu3DTex;
#define MAP_3DTEXT( TexIndex ) \
    glTexCoord3f(0.0f, 0.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(-dOrthoSize,-dOrthoSize,TexIndex);\
    glTexCoord3f(1.0f, 0.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(dOrthoSize,-dOrthoSize,TexIndex);\
    glTexCoord3f(1.0f, 1.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(dOrthoSize,dOrthoSize,TexIndex);\
    glTexCoord3f(0.0f, 1.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(-dOrthoSize,dOrthoSize,TexIndex);
void main(int argc, char **argv)
{

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutCreateWindow("Name");


    char* chBuffer = new char[64];
    for (int i = 0; i < 64; ++i)
        chBuffer[i] = ((i + (i / 8)) % 2) * 128 + 127;


    char* chRGBABuffer = new char[256];
    glGenTextures(1, (GLuint*)&mu3DTex);



    glBindTexture(GL_TEXTURE_3D, mu3DTex);
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);



    for (int nIndx = 0; nIndx < 64; ++nIndx)
    {
        chRGBABuffer[nIndx * 4] = chBuffer[nIndx];
        chRGBABuffer[nIndx * 4 + 1] = chBuffer[nIndx];
        chRGBABuffer[nIndx * 4 + 2] = chBuffer[nIndx];
        chRGBABuffer[nIndx * 4 + 3] = chBuffer[nIndx];
    }

    glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA, 4, 4, 4, 0,
        GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid *)chRGBABuffer);
    glBindTexture(GL_TEXTURE_3D, 0);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glEnable(GL_ALPHA_TEST);
    glAlphaFunc(GL_GREATER, 0.03f);

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    glMatrixMode(GL_TEXTURE);
    glLoadIdentity();


    glEnable(GL_TEXTURE_3D);
    glBindTexture(GL_TEXTURE_3D, mu3DTex);

    for (float fIndx = -1.0f; fIndx <= 1.0f; fIndx += 0.003f)
    {
        glBegin(GL_QUADS);
        MAP_3DTEXT(fIndx);
        glEnd();
    }
    system("pause");


}

Answer 1

这是100％不是如何使用GLUT。

你需要：

设置glutDisplayFunc()回拨
在结尾处致电glFlush()
在glutMainLoop()中拨打main()，而不是在墙上投掷GL命令并希望获得最佳效果

像这样（未经测试）：

#include <glut.h>
#include <GL/gl.h>

GLfloat dOrthoSize = 1.0f;

#define MAP_3DTEXT( TexIndex ) \
    glTexCoord3f(0.0f, 0.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(-dOrthoSize,-dOrthoSize,TexIndex);\
    glTexCoord3f(1.0f, 0.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(dOrthoSize,-dOrthoSize,TexIndex);\
    glTexCoord3f(1.0f, 1.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(dOrthoSize,dOrthoSize,TexIndex);\
    glTexCoord3f(0.0f, 1.0f, ((float)TexIndex+1.0f)/2.0f);  \
    glVertex3f(-dOrthoSize,dOrthoSize,TexIndex);

GLuint mu3DTex;
void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_TEXTURE);
    glLoadIdentity();

    glEnable(GL_ALPHA_TEST);
    glAlphaFunc(GL_GREATER, 0.03f);

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    glEnable(GL_TEXTURE_3D);
    glBindTexture(GL_TEXTURE_3D, mu3DTex);

    glBegin(GL_QUADS);
    for (float fIndx = -1.0f; fIndx <= 1.0f; fIndx += 0.003f)
    {
        MAP_3DTEXT(fIndx);
    }
    glEnd();

    glFlush();
}

void main(int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(500, 500);
    glutCreateWindow("Name");

    char* chBuffer = new char[64];
    for (int i = 0; i < 64; ++i)
        chBuffer[i] = ((i + (i / 8)) % 2) * 128 + 127;

    char* chRGBABuffer = new char[256];
    glGenTextures(1, (GLuint*)&mu3DTex);

    glBindTexture(GL_TEXTURE_3D, mu3DTex);
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_BORDER);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    for (int nIndx = 0; nIndx < 64; ++nIndx)
    {
        chRGBABuffer[nIndx * 4] = chBuffer[nIndx];
        chRGBABuffer[nIndx * 4 + 1] = chBuffer[nIndx];
        chRGBABuffer[nIndx * 4 + 2] = chBuffer[nIndx];
        chRGBABuffer[nIndx * 4 + 3] = chBuffer[nIndx];
    }

    glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA, 4, 4, 4, 0,
        GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid *)chRGBABuffer);
    glBindTexture(GL_TEXTURE_3D, 0);

    glutDisplayFunc( display );
    glutMainLoop();
}

黑屏与GLUT？

1 个答案: