Draw multiple objects with textures

Question

I want to draw cubes using textures.

void OperateWithMainMatrix(ESContext* esContext, GLfloat offsetX, GLfloat offsetY, GLfloat offsetZ) {

UserData *userData = (UserData*) esContext->userData;
ESMatrix modelview;
ESMatrix perspective;
    //Manipulation with matrix 
    ...
    glVertexAttribPointer(userData->positionLoc, 3, GL_FLOAT, GL_FALSE, 0, cubeFaces);
    //in cubeFaces coordinates verticles cube
    glVertexAttribPointer(userData->normalLoc, 3, GL_FLOAT, GL_FALSE, 0, cubeFaces);
    //for normals (use in fragment shaider for textures)

    glEnableVertexAttribArray(userData->positionLoc);
    glEnableVertexAttribArray(userData->normalLoc);

    // Load the MVP matrix
    glUniformMatrix4fv(userData->mvpLoc, 1, GL_FALSE, 
                       (GLfloat*)&userData->mvpMatrix.m[0][0]);

    //Bind base map
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_CUBE_MAP, userData->baseMapTexId);

    //Set the base map sampler to texture unit to 0
    glUniform1i(userData->baseMapLoc, 0);

   // Draw the cube
    glDrawArrays(GL_TRIANGLES, 0, 36);
   }

(coordinates transformation is in OperateWithMainMatrix() ) Then Draw() function is called:

void Draw(ESContext *esContext)
{
   UserData *userData = esContext->userData;
   // Set the viewport
   glViewport(0, 0, esContext->width, esContext->height);

   // Clear the color buffer
   glClear(GL_COLOR_BUFFER_BIT);

   // Use the program object
   glUseProgram(userData->programObject);

  OperateWithMainMatrix(esContext, 0.0f, 0.0f, 0.0f);

  eglSwapBuffers(esContext->eglDisplay, esContext->eglSurface);
}

This work fine, but if I try to draw multiple cubes (next code for example):

void Draw(ESContext *esContext)
{ ...

    // Use the program object
    glUseProgram(userData->programObject);

    OperateWithMainMatrix(esContext, 2.0f, 0.0f, 0.0f);
    OperateWithMainMatrix(esContext, 1.0f, 0.0f, 0.0f);
    OperateWithMainMatrix(esContext, 0.0f, 0.0f, 0.0f);
    OperateWithMainMatrix(esContext, -1.0f, 0.0f, 0.0f);
    OperateWithMainMatrix(esContext, -2.0f, 0.0f, 0.0f);
    eglSwapBuffers(esContext->eglDisplay, esContext->eglSurface);
}

A side faces overlapes frontal face. The side face of the right cube overlaps frontal face of the center cube. How can i remove this effect and display miltiple cubes without it?

score 0 · Accepted Answer · answered Oct 05 '12 at 14:10

You need to turn on depth testing:

    gl.glClearDepth(1.0f); // Set depth's clear-value to farthest
    gl.glEnable(GL2.GL_DEPTH_TEST); // Enables depth-buffer for hidden
                                    // surface removal
    gl.glDepthFunc(GL2.GL_LEQUAL); // The type of depth testing to do

Draw multiple objects with textures

1 Answers1