Question

我正在为我的OpenGLES 2.0渲染器编写一个灯光着色器。我已经搞乱了一个示例项目的着色器，并且已经开始使用定向照明。但是当我尝试将它实现到我们自己的代码中时，它的行为非常奇怪 - 某些部分看起来似乎在他们不应该等等时点亮。

我会在此处发布着色器代码，如果您想要更多，请提出要求。我和一个队友一直试图解决这个过去一周半没有进展，我们真的需要一些帮助。感谢。

final String vertexShader =
            "uniform mat4 u_MVPMatrix;"     // A constant representing the combined model/view/projection matrix.
                    + "uniform mat4 u_MVMatrix;"        // A constant representing the combined model/view matrix.
                    + "uniform vec3 u_LightPos;"        // The position of the light in eye space.
                    + "uniform vec3 u_VectorToLight;"

                    + "attribute vec4 a_Position;"      // Per-vertex position information we will pass in.
                    + "attribute vec4 a_Color;"     // Per-vertex color information we will pass in.
                    + "attribute vec3 a_Normal;"        // Per-vertex normal information we will pass in.


                    + "varying vec4 v_Color;"       // This will be passed into the fragment shader.

                    +"vec3 modelViewVertex;"
                    +"vec3 modelViewNormal;"

                    +"vec4 getPointLighting();"
                    +"vec4 getAmbientLighting();"
                    +"vec4 getDirectionalLighting();"
                    + "void main()"     // The entry point for our vertex shader.
                    + "{"
                    // Transform the vertex into eye space.
                    + "   modelViewVertex = vec3(u_MVMatrix * a_Position);"
                    // Transform the normal's orientation into eye space.
                    + "   modelViewNormal = vec3(u_MVMatrix * vec4(a_Normal, 0.0));"
                    // Will be used for attenuation.

                    // Multiply the color by the illumination level. It will be interpolated across the triangle.
                   // + "   v_Color = getAmbientLighting();"
                    + "   v_Color = getDirectionalLighting();"
                    //+ "   v_Color += getPointLighting();                                       \n"

                    // gl_Position is a special variable used to store the final position.
                    // Multiply the vertex by the matrix to get the final point in normalized screen coordinates.
                    + "   gl_Position = u_MVPMatrix * a_Position;"
                    + "}"

                    + "vec4 getAmbientLighting(){"
                    + "   return a_Color * 0.1;"
                    + "}"

                    + "vec4 getPointLighting(){"
                    + "   float distance = length(u_LightPos - modelViewVertex);"
                    // Get a lighting direction vector from the light to the vertex.
                    + "   vec3 lightVector = normalize(u_LightPos - modelViewVertex);"
                    // Calculate the dot product of the light vector and vertex normal. If the normal and light vector are
                    // pointing in the same direction then it will get max illumination.
                    + "   float diffuse = max(dot(modelViewNormal, lightVector), 0.0);"
                    // Attenuate the light based on distance.
                    + "   diffuse = diffuse * (1.0 / (1.0 + distance));" +
                    "   return a_Color * diffuse;"
                    +"}"

                    +"vec4 getDirectionalLighting(){" +

                        "vec3 lightVector = normalize(u_VectorToLight - modelViewVertex);"+
                        "float diffuse = max(dot(modelViewNormal, lightVector), 0.0);" +
                        "diffuse *= .3;"+
                        "return a_Color * diffuse;"+
                    "}";

我已将所有内容留在那里，即使是我们放弃的内容。再次感谢。

编辑：我可能也应该认为变换是标准的;通过改变视图矩阵来旋转和移动摄像机，通过改变模型矩阵来旋转对象。

Answer 1

在定向照明模型中，所有光线都以单一，均匀的方向拍摄，换句话说，它们都是相互平行的。但是，在函数getDirectionalLighting（）中，lightVector依赖于modelViewVertex，而这似乎是导致问题的原因。尝试将其更改为

vec3 lightVector = normalize(u_VectorToLight);

或只是

vec3 lightVector = normalize(-u_LightPos);

OpenGL ES 2.0定向照明问题（漫反射）

1 个答案: