基于2D纹理的体绘制

时间：2014-04-13 19:24:48

标签： c++ opengl volume-rendering gltools

我在互联网上找到了一个精彩的体积渲染教程： volume rendering tutorial 。示例代码是用Windows编写的，因为我在Mac上工作，所以根据我的理解，我尝试编写自己的代码。现在，我的程序只是在Z轴上排列从-1到1的2D帧，而不应用alpha和blend。所以如果一切顺利，我应该能够看到第一片。但是，当我运行该程序时，我得到一些奇怪的东西。

我的代码：

//
//  VolumeRendering.cpp
//  Volume_Rendering
//
//  Created by HOBBY on 4/5/14.
//  Copyright (c) 2014 Yihao Jiang. All rights reserved.
//
#include <GLTools.h>
#include <GL/glew.h>
#include <Opengl/gl.h>
#include <glut/glut.h>
#include <fstream>
#include "VolumeRendering.h"
#include <GLMatrixStack.h>
#include <GLFrustum.h>
#include <GLGeometryTransform.h>

int m_uImageCount;
int m_uImageWidth;
int m_uImageHeight;
GLuint* m_puTextureIDs;

GLMatrixStack modelViewMatrix;
GLMatrixStack projectionMatrix;
GLFrame       cameraFrame;
GLFrustum     viewFrustum;
GLBatch       myBatch;
GLGeometryTransform    transformPipeline;
GLShaderManager        shaderManager;

void ChangeSize(int w, int h)
{
   glViewport(0, 0, w, h);
   GLdouble aspectRatio = (GLdouble)(w)/(GLdouble)(h);
   if (w <= h)
   {
       viewFrustum.SetOrthographic(-1.0f, 1.0f, -(1.0f/aspectRatio), 1.0f/aspectRatio, -1.0f, 1.0f);
   }
   else
   {
       viewFrustum.SetOrthographic(-1.0f, 1.0f, -(1.0f * aspectRatio), 1.0f * aspectRatio, -1.0f, 1.0f);
   }
   projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
   transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);

}

void SetupRC()
{
   glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
   shaderManager.InitializeStockShaders();

   glEnable(GL_DEPTH_TEST);

   const char* filePath = "/Users/WensarHobby/Documents/Codes/workspace/Volume_Rendering/Volume_Rendering/head256x256x109";
   if(!InitTextures2D(filePath))
   {
       printf("InitTexture error");
   }

}

bool InitTextures2D(const char* filePath)
{
    std::fstream myFile;
    myFile.open(filePath, std::ios::in | std::ios::binary);

    m_uImageCount = 109;
    m_uImageWidth = 256;
    m_uImageHeight = 256;

    // Holds the texuture IDs
    m_puTextureIDs = new GLuint[m_uImageCount];

    // Holds the luminance buffer
    char* chBuffer = new char[m_uImageWidth * m_uImageHeight];
    char* chRGBABuffer = new char[m_uImageWidth * m_uImageHeight * 4];
    glGenTextures(m_uImageCount, (GLuint*)m_puTextureIDs);

    // Read each frames and construct the texture
    for( int nIndx = 0; nIndx < m_uImageCount; ++nIndx )
    {
        // Read the frame
        myFile.read(chBuffer, m_uImageWidth*m_uImageHeight);

        // Set the properties of the texture.
        glBindTexture( GL_TEXTURE_2D, m_puTextureIDs[nIndx] );
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, m_uImageWidth, m_uImageHeight , 0,
                 GL_LUMINANCE, GL_UNSIGNED_BYTE,(GLvoid *) chBuffer);
        glBindTexture( GL_TEXTURE_2D, 0 );
    }

    delete[] chBuffer;
    delete[] chRGBABuffer;
    return true;
}

void SpecialKeys(int key, int x, int y)
{
    if(key == GLUT_KEY_UP)
    {}

    if (key == GLUT_KEY_DOWN)
    {

    }

    if (key == GLUT_KEY_LEFT)
    {

    }

    if (key == GLUT_KEY_RIGHT)
    {

    }

    glutPostRedisplay();
}

void RenderScene(void)
{
    static GLfloat vLightPos [] = { 1.0f, 1.0f, 0.0f };
    static GLfloat vWhite [] = { 1.0f, 1.0f, 1.0f, 1.0f };

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);


    modelViewMatrix.PushMatrix();
    M3DMatrix44f mCamera;
    cameraFrame.GetCameraMatrix(mCamera);
    modelViewMatrix.MultMatrix(mCamera);

    for(int nIndx=0; nIndx <m_uImageCount;++nIndx)
    {
        glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
        MakeQuads(nIndx);
        glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);

    }


    shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
                             transformPipeline.GetModelViewMatrix(),
                             transformPipeline.GetProjectionMatrix(),
                             vLightPos, vWhite, 0);
    myBatch.Draw();


    modelViewMatrix.PopMatrix();

    glutSwapBuffers();

}

void MakeQuads(int quads_index)
{
    myBatch.Begin(GL_QUADS, 4, 1);
    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(quads_index, 0.0f, 0.0f);
    myBatch.Vertex3f(-1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(quads_index, 1.0f, 0.0f);
    myBatch.Vertex3f(1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(quads_index, 0.0f, 1.0f);
    myBatch.Vertex3f(-1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(quads_index, 1.0f, 1.0f);
    myBatch.Vertex3f(1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
    myBatch.End();
}

void ShutdownRC(void)
{
    glDeleteTextures(m_uImageCount, (GLuint*)m_puTextureIDs);
}


int main(int argc, char* argv[])
{
    gltSetWorkingDirectory(argv[0]);
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
    glutInitWindowSize(400, 400);
    glutCreateWindow("Volume_Rendering");
    glutReshapeFunc(ChangeSize);
    glutSpecialFunc(SpecialKeys);
    glutDisplayFunc(RenderScene);

    GLenum err = glewInit();
    if (GLEW_OK != err) {
        fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
        return 1;
    }

    SetupRC();

    glutMainLoop();
    ShutdownRC();
    return 0;

}

这是我奇怪的结果： weird result

我是OpenGL和卷渲染的新手，在我看来，我使用着色器管理器应该有问题。但我不太确定。谁能告诉我问题出在哪里？非常感谢你。

1 个答案:

答案 0 :(得分：1)

最后，我明白了！我是对的，问题在于MultiTexCoord2f（）函数。此函数的第一个参数应始终为0而不是quads_​​index。这里没有多重纹理!!新代码如下所示：

#include <GLTools.h>
#include <GL/glew.h>
#include <Opengl/gl.h>
#include <glut/glut.h>
#include <fstream>
#include "VolumeRendering.h"
#include <GLMatrixStack.h>
#include <GLFrustum.h>
#include <GLGeometryTransform.h>

int m_uImageCount;
int m_uImageWidth;
int m_uImageHeight;
GLuint* m_puTextureIDs;

GLMatrixStack modelViewMatrix;
GLMatrixStack projectionMatrix;
GLFrame       cameraFrame;
GLFrame       objectFrame;
GLFrustum     viewFrustum;
GLBatch       myBatch;
GLGeometryTransform    transformPipeline;
GLShaderManager        shaderManager;

void ChangeSize(int w, int h)
{
    glViewport(0, 0, w, h);
    viewFrustum.SetPerspective(35.0f, float(w) / float(h), 1.0f, 500.0f);
    projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
    transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}    

void SetupRC()
{
    glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
    shaderManager.InitializeStockShaders();

    glEnable(GL_DEPTH_TEST);

    const char* filePath =     "/Users/WensarHobby/Documents/Codes/workspace/Volume_Rendering/Volume_Rendering/head256x256x109";
    if(!InitTextures2D(filePath))
    {
        printf("InitTexture error");
    }

    cameraFrame.MoveForward(-7.0f);
}

bool InitTextures2D(const char* filePath)
{
    std::fstream myFile;
    myFile.open(filePath, std::ios::in | std::ios::binary);

    m_uImageCount = 109;
    m_uImageWidth = 256;
    m_uImageHeight = 256;

    // Holds the texuture IDs
    m_puTextureIDs = new GLuint[m_uImageCount];

    // Holds the luminance buffer
    char* chBuffer = new char[m_uImageWidth * m_uImageHeight];
    //char* chRGBABuffer = new char[m_uImageWidth * m_uImageHeight * 4];
    glGenTextures(m_uImageCount, m_puTextureIDs);

    // Read each frames and construct the texture
    for( int nIndx = 0; nIndx < m_uImageCount; ++nIndx )
    {
        // Read the frame
        myFile.read(chBuffer, m_uImageWidth*m_uImageHeight);

        // Set the properties of the texture.
        glBindTexture( GL_TEXTURE_2D, m_puTextureIDs[nIndx] );
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, m_uImageWidth, m_uImageHeight , 0,
                 GL_LUMINANCE, GL_UNSIGNED_BYTE,(GLvoid *) chBuffer);
        glBindTexture( GL_TEXTURE_2D, 0 );
    }

    delete[] chBuffer;
   // delete[] chRGBABuffer;
    return true;
}

void SpecialKeys(int key, int x, int y)
{
glutPostRedisplay();
}

void RenderScene(void)
{
    static GLfloat vLightPos [] = { 1.0f, 1.0f, 0.0f };
    static GLfloat vWhite [] = { 1.0f, 1.0f, 1.0f, 1.0f };

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);


    modelViewMatrix.PushMatrix();
    M3DMatrix44f mCamera;
    cameraFrame.GetCameraMatrix(mCamera);
    modelViewMatrix.MultMatrix(mCamera);

    M3DMatrix44f mObjectFrame;
    objectFrame.GetMatrix(mObjectFrame);
    modelViewMatrix.MultMatrix(mObjectFrame);

    for(int nIndx=0; nIndx <m_uImageCount;++nIndx)
    {
        glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
        MakeQuads(nIndx);
        glBindTexture(GL_TEXTURE_2D, m_puTextureIDs[nIndx]);
        shaderManager.UseStockShader(GLT_SHADER_TEXTURE_POINT_LIGHT_DIFF,
                                 transformPipeline.GetModelViewMatrix(),
                                 transformPipeline.GetProjectionMatrix(),
                                 vLightPos, vWhite, 0);
        myBatch.Draw();
    }

    modelViewMatrix.PopMatrix();

    glutSwapBuffers();

}

void MakeQuads(int quads_index)
{
    myBatch.Begin(GL_QUADS, 4, 1);

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(0, 0.0f, 0.0f);
    myBatch.Vertex3f(-1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
    //myBatch.Vertex3f(-1.0f, -1.0f, 1.0f);

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(0, 1.0f, 0.0f);
    myBatch.Vertex3f(1.0f, -1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
    //myBatch.Vertex3f(1.0f, -1.0f, 1.0f);

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(0, 1.0f, 1.0f);
    myBatch.Vertex3f(1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
    //myBatch.Vertex3f(1.0f, 1.0f, 1.0f);

    myBatch.Normal3f(0.0f, 0.0f, -1.0f);
    myBatch.MultiTexCoord2f(0, 0.0f, 1.0f);
    myBatch.Vertex3f(-1.0f, 1.0f, 1.0f - (GLfloat)(quads_index/m_uImageCount));
    //myBatch.Vertex3f(-1.0f, 1.0f, 1.0f);

    myBatch.End();
}

void ShutdownRC(void)
{
    glDeleteTextures(m_uImageCount, (GLuint*)m_puTextureIDs);
}


int main(int argc, char* argv[])
{    
    gltSetWorkingDirectory(argv[0]);
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
    glutInitWindowSize(400, 400);
    glutCreateWindow("Volume_Rendering");
    glutReshapeFunc(ChangeSize);
    glutSpecialFunc(SpecialKeys);
    glutDisplayFunc(RenderScene);

    GLenum err = glewInit();
    if (GLEW_OK != err) {
        fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
        return 1;
    }

    SetupRC();

    glutMainLoop();

    ShutdownRC();
    return 0;

}
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