多维数据集没有在OpenGL中呈现
多维数据集没有在OpenGL中呈现
提问于 2013-10-26 17:43:43
我试图用着色器、缓冲区等绘制一个立方体，编写一个基本的OpenGL 3.3程序。问题是没有绘制多维数据集。很抱歉出现了这么多代码，但我觉得错误可能在任何地方，因为在我看来，这一切似乎都是正确的:显示函数是循环的，着色器是编译的，矩阵被传递给着色器。我怀疑淘汰可能有问题。请看一下。下面是代码(我使用freeglut，首先调用init()，然后在循环中显示运行)：
初始化代码：
struct ProgramData
{
GLuint theProgram;
GLuint iModel;
GLuint iView;
GLuint iProjection;
};
ProgramData shaderProgram;
ProgramData LoadProgram(const std::string &strVertexShader,
const std::string &strFragmentShader)
{
std::vector<GLuint> shaderList;
shaderList.push_back(LoadShader(GL_VERTEX_SHADER, strVertexShader));
shaderList.push_back(LoadShader(GL_FRAGMENT_SHADER, strFragmentShader));
ProgramData data;
data.theProgram = CreateProgram(shaderList);
data.iModel = glGetUniformLocation(data.theProgram, "mModel");
data.iView = glGetUniformLocation(data.theProgram, "mView");
data.iProjection = glGetUniformLocation(data.theProgram, "mProjection");
return data;
}
float cube_vertices[] = {
-1.0f, -1.0f, 1.0f,
1.0f, -1.0f, 1.0f,
1.0f, 1.0f, 1.0f,
-1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, -1.0f,
1.0f, -1.0f, -1.0f,
1.0f, 1.0f, -1.0f,
-1.0f, 1.0f, -1.0f,
GREEN_COLOR,
BLUE_COLOR,
RED_COLOR,
BROWN_COLOR,
GREEN_COLOR,
BLUE_COLOR,
RED_COLOR,
BROWN_COLOR,
};
GLubyte cube_elements[] = {
0,1,2, 2,3,0,
0,3,4, 4,5,0,
0,5,6, 6,1,0,
1,6,7, 7,2,1,
7,4,3, 3,2,7,
4,7,6, 6,5,4
};
void InitializeProgram()
{
//initialize vertex buffer
glGenBuffers(1, &vertex_buffer_obj);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_obj);
glBufferData(GL_ARRAY_BUFFER, sizeof(cube_vertices),
cube_vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
//initialize index buffer
glGenBuffers(1, &index_buffer_obj);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_obj);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(cube_elements),
cube_elements, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
shaderProgram = LoadProgram("shader.vert", "shader.frag");
}
void init()
{
InitializeProgram();
int numberOfVertices = 8;
size_t color_data_offset = sizeof(float) * 3 * numberOfVertices;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_obj);
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0,
(void*)color_data_offset);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_obj);
glBindVertexArray(0);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);
glFrontFace(GL_CW);
glEnable(GL_DEPTH_TEST);
glDepthMask(GL_TRUE);
glDepthFunc(GL_LEQUAL);
glDepthRange(0.0f, 1.0f);
}顶点着色器：
#version 330
layout (location = 0) in vec3 inPosition;
layout (location = 1) in vec3 color;
uniform mat4 mProjection;
uniform mat4 mView;
uniform mat4 mModel;
smooth out vec3 theColor;
void main()
{
gl_Position = mProjection * mView * mModel * vec4(inPosition, 1);
theColor = color;
}碎片着色器：
#version 330
smooth in vec3 theColor;
out vec4 outputColor;
void main()
{
outputColor = vec4(theColor, 1);
}绘制代码：
glm::vec3 cam_pos(3, 2, 3);
void display()
{
glClearColor(0.3f, 0.3f, 0.3f, 1.0f);
glClearDepth(1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(shaderProgram.theProgram);
glm::mat4 model_matrix = glm::translate(glm::vec3(0, 0, 0));
glm::mat4 view_matrix = glm::lookAt(cam_pos,
glm::vec3(0, 0, 0), glm::vec3(0, 0, 1));
glm::mat4 proj_matrix = glm::perspective(45.0f, 1.0f, 1.0f, 100.0f);
glUniformMatrix4fv(shaderProgram.iProjection, 1,
GL_FALSE, glm::value_ptr(proj_matrix));
glUniformMatrix4fv(shaderProgram.iView, 1,
GL_FALSE, glm::value_ptr(view_matrix));
glUniformMatrix4fv(shaderProgram.iModel, 1,
GL_FALSE, glm::value_ptr(model_matrix));
glBindVertexArray(vao);
int size; glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER,
GL_BUFFER_SIZE, &size);
glDrawElements(GL_TRIANGLES, size / sizeof(GLubyte), GL_UNSIGNED_SHORT, 0);
glBindVertexArray(0);
glUseProgram(0);
glutSwapBuffers();
glutPostRedisplay();
}UPD:在init方法中，当计算颜色的偏移量应该是sizeof(float) * 3 * numberOfVertices而不是sizeof(GLubyte) * 3 * numberOfVertices时，颜色作为浮动存储。渲染问题没有解决。
解题:谢谢你的帮助。见下面的答案。
回答 2
Stack Overflow用户
回答已采纳
发布于 2013-10-27 00:01:38
In display()函数
glDrawElements(GL_TRIANGLES, size / sizeof(GLubyte), GL_UNSIGNED_SHORT, 0);应改为
glDrawElements(GL_TRIANGLES, size / sizeof(GLubyte), GL_UNSIGNED_BYTE, 0);和init()
glFrontFace(GL_CW);至
glFrontFace(GL_CCW);所以问题是我传递给了OpenGL不正确的数据。索引数组是GLUbyte (每个数组元素的大小为1字节)，但由于某种原因，我决定它是GLushort (2字节)。
编辑:不重要，但是向上向量(生成相机矩阵时)不应该是glm::vec3(0, 0, 1)，而应该是glm::vec3(0, 1, 0)。
Stack Overflow用户
发布于 2013-10-26 17:49:35
在浏览代码时，我注意到了顶点着色器中的一行代码：
gl_Position = mProjection * mView * mModel * vec4(inPosition, 0);0真的应该是一个1.0。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/19609867
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