如何创建OpenGL ES 2.0 SkyBox？

Question

你能给我提供一些OpenGL ES 2.0中好的SkyBox示例吗？我只找到了OpenGL的示例，但对我来说不起作用。 我是这样做的： 初始化：

glUseProgram(m_programSkyBox.Program);
glGenBuffers(1, &skyBoxVertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, skyBoxVertexBuffer);


float vertices[24] = {  
    -1.0, -1.0,  1.0,
    1.0, -1.0,  1.0,
    -1.0,  1.0,  1.0,
    1.0,  1.0,  1.0,
    -1.0, -1.0, -1.0,
    1.0, -1.0, -1.0,
    -1.0,  1.0, -1.0,
    1.0,  1.0, -1.0,
};

glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

glGenBuffers(1, &skyBoxIndexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, skyBoxIndexBuffer);


GLubyte indices[14] = {0, 1, 2, 3, 7, 1, 5, 4, 7, 6, 2, 4, 0, 1};
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

绘制天空盒：

glClearColor(0.5f, 0.5f, 0.5f, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(m_programSkyBox.Program);

glDisable(GL_DEPTH_TEST);   // skybox should be drawn behind anything else
glBindTexture(GL_TEXTURE_CUBE_MAP, m_textures.Cubemap);


glBindBuffer(GL_ARRAY_BUFFER, skyBoxVertexBuffer);
glVertexAttribPointer(m_programSkyBox.Attributes.Position, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glEnableVertexAttribArray(m_programSkyBox.Attributes.Position);
glBindBuffer(GL_ARRAY_BUFFER, 0);

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, skyBoxIndexBuffer);
glDrawElements(GL_TRIANGLE_STRIP, 14, GL_UNSIGNED_BYTE, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glEnable(GL_DEPTH_TEST);

纹理加载正常工作。着色器正确编译，看起来像这样： 顶点着色器：

attribute vec4 position;
varying mediump vec3 texCoord;
void main() {
   texCoord.xyz = position.xyz;
}

片元着色器：

uniform samplerCube Sampler;

varying mediump vec3 texCoord;

 void main() {
     mediump vec3 cube = vec3(textureCube(Sampler, texCoord.xyz));
     gl_FragColor = vec4(cube, 1.0);
 }

但是我无法看到立方体。我做错了什么吗？ 谢谢

- Martin Pilch

Answer 1

抱歉，我找到了问题所在。我在顶点着色器中没有“创建”顶点。应该是这样的：

uniform mat4 modelViewMatrix;
  uniform mat4 projectionMatrix;

    attribute vec4 position;
    varying mediump vec4 texCoord;
    void main() {
        texCoord = position;
        gl_Position = projectionMatrix * modelViewMatrix * position;

    }

- Martin Pilch

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请问您是否有创建GL_TEXTURE_CUBE_MAP纹理的源代码？此外，不好意思打扰，我想请教一下Necroing。 - sgtHale