Question

有许多3D对象（1000+）由三角形构成，我需要使用Android NDK和OpenGL ES 2.0绘制它。每个三角形都有顶点坐标，颜色，纹理和纹理坐标。我有两个问题：

我的片段着色器中的函数texture2D(u_Texture,v_TexCoord)会为每个三角形返回vec4(0.0, 0.0, 0.0, 1.0)。
低费率框架。

这是我的代码：

加载bmp文件并创建纹理：

void CreateTexture(unsigned &texture, const char * fileName)
{
    char *pFolderName = NULL;
    int width = 0;
    int height = 0;
    unsigned char *data = NULL;
    char *pExtension = NULL;
    glGenTextures(1, &texture);
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    //check extension
    pExtension = new char[5];
    pExtension[4] = '\0';
    int j = strlen(fileName) - 1;
    do {
        j--;
    } while (j > 0 && fileName[j] != '.');

    for (int k = 0; k < 5; k++) {
        j++;
        pExtension[k] = fileName[j];
    }
    if (   0 == strcmp(pExtension, BMP_EXT)
        || 0 == strcmp(pExtension, BMP_EXT1))
    {
        FILE *f = fopen(fileName, "r");
        if(f == NULL) LOGE("Couldn't open texture file %s", fileName);
        fseek(f, 18, SEEK_SET);
        fread(&width, 4, 1, f);
        fread(&height, 4, 1, f);
        data = new unsigned char[width*height*3];
        fseek(f, 54, SEEK_SET);
        fread(data, width*height*3, 1, f);

        char tmp;
        //convert BGR->RGB
        for(int i=0;i<width*height*3-2;i+=3)
        {
            tmp = data[i];
            data[i] = data[i+2];
            data[i+2] = tmp;
        }
        unsigned char *reverseData = new unsigned char[width*height*3];
        for(int j1 = 0; j1 < height; ++j1)
        for(int i1 = 0; i1 < width*3; ++i1)
            reverseData[j1*(width*3)+i1] = data[(height-j1-1)*width*3+i1];
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, reverseData);
        delete []data;
        delete []pExtension;
        delete []reverseData;
    }
}

绘制功能：

void Display(VisObject *obj)
{
    GLint pos = shader.GetAttribLocation("a_Position");
    GLint texpos = shader.GetAttribLocation("a_TexCoord");
    GLint a_color = shader.GetAttribLocation("a_Color");
    GLint texture  = shader.GetUniformLocation("u_Texture");
    GLint textureFlag  = shader.GetUniformLocation("u_TextureFlag");
    for(int i=0; i < obj->CountTr ; i++)
    {
        if (!obj->m_visible) return;

        float color[12];
        if(obj->triangles[i].color[0] < 0)
        {
            color[0] = 1.0f; color[1] = 1.0f; color[2] = 1.0f;color[3] = obj->m_vis_koef;
            color[4] = 1.0f; color[5] = 1.0f; color[6] = 1.0f;color[7] = obj->m_vis_koef;
            color[8] = 1.0f; color[9] = 1.0f; color[10] = 1.0f;color[11] = obj->m_vis_koef;
        }
        else
        {
            color[0]  = obj->triangles[i].color[0]; color[1]  = obj->triangles[i].color[1];
            color[2]  = obj->triangles[i].color[2]; color[3]  = obj->triangles[i].color[3];

            color[4]  = obj->triangles[i].color[0]; color[5]  = obj->triangles[i].color[1];
            color[6]  = obj->triangles[i].color[2]; color[7]  = obj->triangles[i].color[3];

            color[8]  = obj->triangles[i].color[0]; color[9]  = obj->triangles[i].color[1];
            color[10] = obj->triangles[i].color[2]; color[11] = obj->triangles[i].color[3];
        }
        glActiveTexture(GL_TEXTURE0);
        if(obj->m_num_texture > 0)
            glBindTexture(GL_TEXTURE_2D,g_Texture[obj->m_num_texture] );
        else
            glBindTexture(GL_TEXTURE_2D, obj->triangles[i].numtex );
        shader.Uniform1i(texture, 0);
        float vertices[] = {
                obj->triangles[i].verts[0].x, obj->triangles[i].verts[0].y, obj->triangles[i].verts[0].z,
                obj->triangles[i].verts[1].x, obj->triangles[i].verts[1].y, obj->triangles[i].verts[1].z,
                obj->triangles[i].verts[2].x, obj->triangles[i].verts[2].y, obj->triangles[i].verts[2].z
        };
        float texcoords[] = {
                obj->triangles[i].tex[0].U, obj->triangles[i].tex[0].V,
                obj->triangles[i].tex[1].U, obj->triangles[i].tex[1].V,
                obj->triangles[i].tex[2].U, obj->triangles[i].tex[2].V
        };
        glVertexAttribPointer(pos, 3, GL_FLOAT, GL_FALSE, 0, vertices);
        checkGlError("glVertexAttribPointer");
        glEnableVertexAttribArray(pos);
        checkGlError("glEnableVertexAttribArray");
        glVertexAttribPointer(texpos, 2, GL_FLOAT, GL_FALSE, 0, texcoords);
        checkGlError("glVertexAttribPointer");
        glEnableVertexAttribArray(texpos);
        checkGlError("glEnableVertexAttribArray");
        shader.Uniform1f(textureFlag, 1.0f);
        glVertexAttribPointer(a_color, 4, GL_FLOAT, GL_FALSE, 0, color);
        checkGlError("glVertexAttribPointer");
        glEnableVertexAttribArray(a_color);
        checkGlError("glEnableVertexAttribArray");
        glDrawArrays(GL_TRIANGLES, 0, 3);
        checkGlError("glDrawArrays");
}

顶点着色器：

attribute vec3 a_Position;
attribute vec2 a_TexCoord;
attribute vec4 a_Color;

varying vec2 v_TexCoord;
varying vec4 v_Color;

uniform mat4 u_projectionMatrix;
uniform mat4 u_modelviewMatrix;

void main(void) 
{
    mat4 mvpMatrix = u_projectionMatrix*u_modelviewMatrix;
    gl_Position = mvpMatrix*vec4(a_Position, 1.0);
    v_TexCoord = a_TexCoord;
    v_Color = a_Color;
}

片段着色器：

precision mediump float;

varying vec2 v_TexCoord;
varying vec4 v_Color;
uniform sampler2D u_Texture;
uniform float u_TextureFlag;

void main(void) 
{
    gl_FragColor = u_TextureFlag*texture2D(u_Texture,v_TexCoord)*v_Color + (1.0 - u_TextureFlag)*v_Color;
}

我试图将顶点数组和其他数据声明为float vertices[3*3*obj->CountTr];，并在循环中设置数组的值。循环后我绘制三角形： glDrawArrays(GL_TRIANGLES, 0, 3*obj->CountTr); 它工作得更快，但我不明白如何在必要时为三角形设置不同的纹理。

如何在OpenGL ES 2.0中绘制许多3d对象？

0 个答案: