c++ - 使用纹理绘制多个对象不起作用

Question

我正在研究 3D 模型加载器。它可以加载我自己的格式。我为 Blender 编写了自己的导出器，效果很好。模型格式可以在一个模型中处理多个网格(对象)。每个网格可以有不同的纹理。我已经编写了一个运行良好但不使用着色器的加载程序。

我切换到着色器，但出了点问题，纹理显示不正确。这是我的绘图函数，我确定这里有错误:

void CModel::draw(glm::mat4 &MVP)
{
    glActiveTexture(GL_TEXTURE0);
    glEnable(GL_TEXTURE_2D);

    for(unsigned int i=0; i<m_numObjects; i++)
    {
        glUseProgram(m_programID);
        glUniformMatrix4fv(m_matrixUniform, 1, GL_FALSE, &MVP[0][0]);

        glBindTexture(GL_TEXTURE_2D, m_textureIDs[i]);
        glUniform1i(m_textureUniform, 0);

        glBindBuffer(GL_ARRAY_BUFFER, m_bufferIDs[i]);

        // vertices
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(
                0,                  // must match the layout in the shader.
                3,                  // size
                GL_FLOAT,           // type
                GL_FALSE,           // normalized?
                sizeof(float)*8,    // stride
                (void*)0            // array buffer offset
        );

        // UVs
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(
                1,
                2,
                GL_FLOAT,
                GL_FALSE,
                sizeof(float)*8,
                (void*)6
        );

        glDrawArrays(GL_TRIANGLES, 0, m_numElements[i]);
        glBindBuffer(GL_ARRAY_BUFFER, 0);

        glUseProgram(0);
    }

    glDisableVertexAttribArray(0);
    glDisableVertexAttribArray(1);
    glDisable(GL_TEXTURE_2D);
}

顶点和片段着色器也运行良好。

以前的版本(没有着色器)是这样的(效果很好):

void CModel::draw()
{
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glEnableClientState(GL_NORMAL_ARRAY);
    glEnableClientState(GL_VERTEX_ARRAY);

    glClientActiveTexture(GL_TEXTURE0);
    glActiveTexture(GL_TEXTURE0);
    glEnable(GL_TEXTURE_2D);

    for(unsigned int i=0; i<m_numObjects; i++)
    {
        glBindTexture(GL_TEXTURE_2D, m_textureIDs[i]);

        glBindBuffer(GL_ARRAY_BUFFER, m_bufferIDs[i]);

        glTexCoordPointer(2, GL_FLOAT, sizeof(float)*8, (float*)(sizeof(float)*6));
        glNormalPointer(     GL_FLOAT, sizeof(float)*8, (float*)(sizeof(float)*3));
        glVertexPointer(  3, GL_FLOAT, sizeof(float)*8, 0);

        glDrawArrays(GL_TRIANGLES, 0, m_numElements[i]);

        glBindBuffer(GL_ARRAY_BUFFER, 0);
    }

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_NORMAL_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);

    glDisable(GL_TEXTURE_2D);
}

这是整个类(class):

#include "global.h"
#include "CModel.h"
#include "CModelLoader.h"
#include "CShaderLoader.h"

CModel::CModel(){}

CModel::~CModel()
{
    // TODO free memory
}

/** @brief Load mbm file
  *
  * @fileName: mdm model file name we want to load and draw
  */
void CModel::init(char *fileName)
{
    CModelLoader   loader;
    CShaderLoader  shaders;

    loader.loadData(fileName);

    loader.createDataArray( m_dataArray,
                            m_dataArraySizes,
                            m_numObjects,
                            m_numElements,
                            m_textureIDs );

    glGenVertexArrays(1, &m_vertexArrayID);
    glBindVertexArray(m_vertexArrayID);

    m_programID      = shaders.loadShaders("vertexshader.vert", "fragmentshader.frag");

    m_bufferIDs      = new unsigned int[m_numObjects];

    glGenBuffers(m_numObjects, m_bufferIDs);
    for(unsigned int i=0; i<m_numObjects; i++)
    {
        glBindBuffer(GL_ARRAY_BUFFER, m_bufferIDs[i]);
        glBufferData(GL_ARRAY_BUFFER, sizeof(float)*m_dataArraySizes[i], m_dataArray[i], GL_STATIC_DRAW);
    }

}

/** @brief Drawing the mdm model
  *
  */
void CModel::draw(glm::mat4 &MVP)
{

    glEnable(GL_TEXTURE_2D);
    glActiveTexture(GL_TEXTURE0);

    for(unsigned int i=0; i<m_numObjects; i++)
    {
        glUseProgram(m_programID);

        unsigned int matrixUniform  = glGetUniformLocation(m_programID, "MVP");
        unsigned int textureUniform = glGetUniformLocation(m_programID, "myTextureSampler");

        glUniformMatrix4fv(matrixUniform, 1, GL_FALSE, &MVP[0][0]);
        glUniform1i(textureUniform, 0);

        glBindTexture(GL_TEXTURE_2D, m_textureIDs[i]);
        glBindBuffer(GL_ARRAY_BUFFER, m_bufferIDs[i]);

        // vertices
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(
                0,                  // must match the layout in the shader.
                3,                  // size
                GL_FLOAT,           // type
                GL_FALSE,           // normalized?
                sizeof(float)*8,    // stride
                (void*)0            // array buffer offset
        );

        // UVs
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(
                1,
                2,
                GL_FLOAT,
                GL_FALSE,
                sizeof(float)*8,
                (void*)6
        );

        glDrawArrays(GL_TRIANGLES, 0, m_numElements[i]);
        glBindBuffer(GL_ARRAY_BUFFER, 0);

        glUseProgram(0);
    }

    glDisableVertexAttribArray(0);
    glDisableVertexAttribArray(1);



    glDisable(GL_TEXTURE_2D);
}

Answer 1

终于解决了。问题是我对顶点、法线和纹理坐标使用了一个数组，而不是存储在单独的数组中并分别绑定(bind)它们。