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我在搅拌机中创建了一个模型并导出到 .obj 文件。我编写了一个解析器，它读取顶点纹理和法线的坐标。我一直将所有坐标除以适用于程序的常数，以减小模式的大小，使其适合屏幕（这是一个临时措施）。这工作正常，除了照明不起作用，当它应该着色时，我留下了一个黑色的 3D 对象。在网上研究之后，我认为这可能是因为法线不是长度为 1？如果这是真的，我如何缩放我的坐标以使其适合屏幕并让照明正常工作？

顶点着色器

//
//  Created by Jake Cunningham on 13/10/2012.
//  Copyright (c) 2012 Jake Cunningham. All rights reserved.
//

attribute vec4 position;
attribute vec3 normal;

varying lowp vec4 colorVarying;

uniform mat4 modelViewProjectionMatrix;
uniform mat3 normalMatrix;

attribute vec2 TextCo;
varying vec2 textCoOut;

void main()
{
vec3 eyeNormal = normalize(normalMatrix * normal);
vec3 lightPosition = vec3(0.0, 0.0, 1.0);
vec4 diffuseColor = vec4(0.4, 0.4, 1.0, 1.0);

float nDotVP = max(0.0, dot(eyeNormal, normalize(lightPosition)));

colorVarying = diffuseColor * nDotVP;

gl_Position = modelViewProjectionMatrix * position;
textCoOut = TextCo;
}

片段着色器：

//  Created by Jake Cunningham on 13/10/2012.
//  Copyright (c) 2012 Jake Cunningham. All rights reserved.
//

varying lowp vec4 colorVarying;

varying lowp vec2 textCoOut;
uniform sampler2D texture;

void main()
{
gl_FragColor = colorVarying * texture2D(texture, textCoOut);

}

来自视图控制器的代码。

glEnable(GL_DEPTH_TEST);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);


glGenVertexArraysOES(1, &_vertexArray);
glBindVertexArrayOES(_vertexArray);

glGenBuffers(1, &_vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, loader.currentCountOfVerticies * sizeof(GLfloat) * 3, arrayOfVerticies, GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 12, BUFFER_OFFSET(0));

glGenVertexArraysOES(1, &_normalArray);
glBindVertexArrayOES(_normalArray);

glGenBuffers(1, &_normalBuffer);
glBindBuffer(GL_ARRAY_BUFFER, _normalBuffer);
glBufferData(GLKVertexAttribNormal, loader.currentCountOfNormals  * sizeof(GLfloat) * 3,loader.arrayOfNormals , GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 12, BUFFER_OFFSET(0));

glGenVertexArraysOES(1, &_textureArray);
glBindVertexArrayOES(_textureArray);

glGenBuffers(1, &_textureBuffer);
glBindBuffer(GL_ARRAY_BUFFER, _textureBuffer);
glBufferData(GL_ARRAY_BUFFER, loader.currentCountOfTextureCoordinates * sizeof(GLfloat) * 2, loader.arrayOftextureCoOrdinates, GL_STATIC_DRAW);

glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, 8, BUFFER_OFFSET(0));


glBindVertexArrayOES(0);
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1 回答 1

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如果您使用着色器，您可以normalize()在 GLSL 代码中对顶点和法线使用该操作。

您还可以查看obj2opengl 脚本，它可以对模型进行缩放、居中和规范化，将 OBJ 文件转换为头文件，以便为 iOS 实现做好准备。我还将该脚本扩展为mtl2opengl以包括对 MTL 文件的支持并使其更轻量级（也带有 Xcode 示例）。

于 2012-12-31T12:28:35.620 回答