Question

我一直在使用Open GL ES 2.0编程指南，并且在关于纹理的第9章之后，我已经设置了相同的像素阵列（2x2-红绿蓝黄），它只显示整个三角形的红色。似乎无法找到问题，我认为我的着色器也很好，请帮助我的代码。

- (void)setupGL
   {
    [EAGLContext setCurrentContext:self.context];

    [self loadShaders];

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_BLEND);
    glBlendFunc(GL_ONE, GL_SRC_COLOR);

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

    glGenBuffers(1, &_vertexBuffer);
    glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(gRectVertexData), gRectVertexData, GL_STATIC_DRAW);

// 2 x 2 Image, 3 bytes per pixel(R, G, B) 
GLubyte pixels[12] =
{
    255,0,0, // Red 
    0,255,0, // Green
    0,0,255, // Blue
    0,255,255 // Yellow 
};
    // Use tightly packed data
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    // Generate a texture object 
glGenTextures(1, &texture[0]);
    // Bind the texture object 
glBindTexture(GL_TEXTURE_2D, texture[0]);
    // Load the texture
glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, 2,2, 0, GL_RGB,
                 GL_UNSIGNED_BYTE, pixels);
// Set the filtering mode
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    GLint SamplerLoc = glGetUniformLocation(_program, "Texture");
glUniform1i(SamplerLoc, 0);

glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 32, BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 32, BUFFER_OFFSET(12));
glEnableVertexAttribArray(GLKVertexAttribTexCoord0);
glVertexAttribPointer(GLKVertexAttribTexCoord0, 2, GL_FLOAT, GL_FALSE, 32, BUFFER_OFFSET(24));

glBindVertexArrayOES(0);

}

我在加载着色器部分

中有这个

glBindAttribLocation(_program, ATTRIB_VERTEX, "position");
glBindAttribLocation(_program, ATTRIB_NORMAL, "normal");
glBindAttribLocation(_program, ATTRIB_TEX, "TexCoordIn");

然后我的顶点着色器和片段着色器如下

attribute vec4 position;
attribute vec3 normal;
attribute vec2 TexCoordIn;

varying lowp vec4 colorVarying;
varying vec2 TexCoordOut;

uniform mat4 modelViewProjectionMatrix;
uniform mat3 normalMatrix;

void main()
{
  vec3 eyeNormal = normalize(normalMatrix * normal);
  vec3 lightPosition = vec3(0.0, 0.0, 1.0);
  vec4 diffuseColor = vec4(0.8, 0.4, 1.0, 1.0);

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

  colorVarying = diffuseColor*nDotVP;

  gl_Position = modelViewProjectionMatrix * position;
  TexCoordOut = TexCoordIn;
}

片段着色器

varying lowp vec4 colorVarying;
varying lowp vec2 TexCoordOut;
uniform sampler2D Texture;

void main()
{
lowp vec4 col = texture2D(Texture, TexCoordOut);
col.x *= colorVarying.x;
col.y *= colorVarying.x;
col.z *= colorVarying.x;
col.a = 1.0;
    gl_FragColor =  col;
}

Answer 1

改变你的电话

glBindAttribLocation(_program, ATTRIB_TEX, "TexCoordIn");

使用GLKVertexAttribTexCoord0代替您的ATTRIB_TEX枚举。

这是OpenGL Game项目中令人讨厌的陷阱。他们在glBindAttribLocation调用位置和法线时使用的枚举成员恰好具有与GLKVertexAttribPosition和GLKVertexAttribNormal枚举相同的值，但这只是巧合。

查看headnoodles上的帖子，了解分步说明。该示例使用GLKit但其他所有内容都应该相同。

Answer 2

如果只输出纹理坐标会怎样？

你看到[0-1]的渐变吗？

需要帮助在使用着色器的Open GL ES 2.0中找到带纹理的代码中的错误

2 个答案: