iPad Opengl ES程序在模拟器上运行良好，但不适用于设备 [英] iPad Opengl ES program works fine on simulator but not device

问题描述

对于设备，我的所有着色器都加载正常，除了一个。对于这个着色器程序，我得到片段程序无法使用当前上下文状态编译错误，当我调用glGetProgramInfoLog（...）时，顶点着色器出现类似错误;

For the device, all of my shaders load fine except one. For this shader program I get "Fragment program failed to compile with current context state" error, followed by a similar error for the vertex shader when I make a call to glGetProgramInfoLog(...);

顶点着色器：

#version 100

uniform mat4 Projection;
uniform mat4 Modelview;
uniform mat4 Rotation;
uniform vec3 Translation;

uniform vec4 LightDirection;
uniform vec4 MaterialDiffuse;
uniform float MaterialShininess;

attribute vec3 position;
attribute vec3 normal;

varying vec4 color;
varying float specularCoefficient;

void main() {
    vec3 _normal = normalize(mat3(Modelview[0].xyz, Modelview[1].xyz, Modelview[2].xyz)*normal); 
    // There is an easier way to do the above using typecast, but is apparently broken

    float NdotL = dot(-_normal, normalize(vec3(LightDirection)));
    if(NdotL < 0.0){
        NdotL = 0.0;
    }
    color = NdotL * MaterialDiffuse;
    float NdotO = dot(-_normal, vec3(0.0, 0.0, -1.0));
    if(NdotO < 0.0){
        NdotO = 0.0;
    }
    specularCoefficient = pow(NdotO, MaterialShininess);

    vec3 p = position + Translation;
    gl_Position = Projection*Modelview*vec4(p, 1.0);
}

片段着色器：

#version 100
precision mediump float;

varying vec4 color;
varying float specularCoefficient;
uniform vec4 MaterialSpecular;

void main(){
    gl_FragColor = vec4((color + specularCoefficient*MaterialSpecular).rgb, 1.0);
}

我不知道发生了什么，特别是因为我有一个类似的程序这与添加纹理坐标完全相同。此外，当我使用glGetShaderiv（theShader，GL_COMPILE_STATUS和& result）链接程序时，我检查了每个着色器的编译状态，并且它们都检查完好。有任何想法吗？

I am not sure what is going on, especially since I have a similar program that is exactly as above with the addition of texture coordinates. Also, I checked the compile status of each shader when I linked the programs using glGetShaderiv(theShader, GL_COMPILE_STATUS, &result) and they all checked out fine. Any ideas?

推荐答案

更改行

gl_FragColor = vec4((color + specularCoefficient*MaterialSpecular).rgb, 1.0);

gl_FragColor = vec4((1.0*color + specularCoefficient*MaterialSpecular).rgb, 1.0);

解决了这个问题。我怀疑它与变化的变量颜色相关的精度有关，用于将行重新排序为

fixes the problem. I suspect it has something to do with precision related to the varying variable color, for a reordering of the line to

gl_FragColor = vec4((MaterialSpecular + specularCoefficient*color).rgb, 1.0);

同样适用。

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