通过取走ComputePositonOffsets（）和AdjustVertexData（）方法，我可以显示一个三角形，但我添加了一些按钮功能来旋转它以查看屏幕中是否有更多其他地方，我无法想象为什么它会产生黑屏。
#include <algorithm>
#include <string>
#include <vector>
#include <stdio.h>
#include <glload/gl_3_2_comp.h>
#include <GL/freeglut.h>
#define ARRAY_COUNT( array ) (sizeof( array ) / (sizeof( array[0] ) * (sizeof( array ) != sizeof(void*) || sizeof( array[0] ) <= sizeof(void*))))
double rotate_y = 0;
double rotate_x = 0;
GLuint CreateShader(GLenum eShaderType, const std::string &strShaderFile) {
GLuint shader = glCreateShader(eShaderType);
const char *strFileData = strShaderFile.c_str();
glShaderSource(shader, 1, &strFileData, NULL);
glCompileShader(shader);
GLint status;
glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
if (status == GL_FALSE) {
GLint infoLogLength;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLogLength);
GLchar *strInfoLog = new GLchar[infoLogLength + 1];
glGetShaderInfoLog(shader, infoLogLength, NULL, strInfoLog);
const char *strShaderType = NULL;
switch (eShaderType) {
case GL_VERTEX_SHADER:
strShaderType = "vertex";
break;
case GL_GEOMETRY_SHADER:
strShaderType = "geometry";
break;
case GL_FRAGMENT_SHADER:
strShaderType = "fragment";
break;
}
fprintf(stderr, "Compile failure in %s shader:\n%s\n", strShaderType,strInfoLog);
delete[] strInfoLog;
}
return shader;
}
GLuint CreateProgram(const std::vector<GLuint> &shaderList) {
GLuint program = glCreateProgram();
for (size_t iLoop = 0; iLoop < shaderList.size(); iLoop++)
glAttachShader(program, shaderList[iLoop]);
glLinkProgram(program);
GLint status;
glGetProgramiv(program, GL_LINK_STATUS, &status);
if (status == GL_FALSE) {
GLint infoLogLength;
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLogLength);
GLchar *strInfoLog = new GLchar[infoLogLength + 1];
glGetProgramInfoLog(program, infoLogLength, NULL, strInfoLog);
fprintf(stderr, "Linker failure: %s\n", strInfoLog);
delete[] strInfoLog;
}
for (size_t iLoop = 0; iLoop < shaderList.size(); iLoop++)
glDetachShader(program, shaderList[iLoop]);
return program;
}
GLuint theProgram;
const std::string strVertexShader("#version 330\n"
"layout(location = 0) in vec4 position;\n"
"void main()\n"
"{\n"
" gl_Position = position;\n"
"}\n");
const std::string strFragmentShader("#version 330\n"
"out vec4 outputColor;\n"
"void main()\n"
"{\n"
" outputColor = vec4(1.0f, 1.0f, 1.0f, 1.0f);\n"
"}\n");
void InitializeProgram() {
std::vector<GLuint> shaderList;
shaderList.push_back(CreateShader(GL_VERTEX_SHADER, strVertexShader));
shaderList.push_back(CreateShader(GL_FRAGMENT_SHADER, strFragmentShader));
theProgram = CreateProgram(shaderList);
std::for_each(shaderList.begin(), shaderList.end(), glDeleteShader);
}
const float vertexPositions2[] = { 0.5, 0.5, 0.5, -0.5, 0.5, 0.5, -0.5, -0.5,
0.5, 0.5, -0.5, 0.5, 0.5, 0.5, 0.5, 0.5, -0.5, 0.5, 0.5, 0.5, 0.5, 0.5,
0.5, -0.5, -0.5, 0.5, -0.5, -0.5, 0.5, 0.5, -0.5, 0.5, 0.5, -0.5, 0.5,
-0.5, -0.5, -0.5, -0.5, -0.5, -0.5, 0.5, -0.5, -0.5, -0.5, 0.5, -0.5,
-0.5, 0.5, -0.5, 0.5, -0.5, -0.5, 0.5, 0.5, -0.5, -0.5, -0.5, -0.5,
-0.5, -0.5, 0.5, -0.5, 0.5, 0.5, -0.5 };
GLuint positionBufferObject;
GLuint vao;
void InitializeVertexBuffer() {
glGenBuffers(1, &positionBufferObject);
glBindBuffer(GL_ARRAY_BUFFER, positionBufferObject);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPositions2), vertexPositions2,
GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
//Called after the window and OpenGL are initialized. Called exactly once, before the main loop.
void init() {
InitializeProgram();
InitializeVertexBuffer();
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
}
void ComputePositionOffsets(float &fXOffset, float &fYOffset) {
const float fLoopDuration = 5.0f;
const float fScale = 3.14159f * 2.0f / fLoopDuration;
float fElapsedTime = glutGet(GLUT_ELAPSED_TIME) / 1000.0f;
float fCurrTimeThroughLoop = fmodf(fElapsedTime, fLoopDuration);
fXOffset = cosf(fCurrTimeThroughLoop * fScale) * 0.5f;
fYOffset = sinf(fCurrTimeThroughLoop * fScale) * 0.5f;
}
void AdjustVertexData(float fXOffset, float fYOffset) {
std::vector<float> fNewData(ARRAY_COUNT(vertexPositions2));
memcpy(&fNewData[0], vertexPositions2, sizeof(vertexPositions2));
for (int iVertex = 0; iVertex < ARRAY_COUNT(vertexPositions2); iVertex +=
4) {
fNewData[iVertex] += fXOffset;
fNewData[iVertex + 1] += fYOffset;
}
glBindBuffer(GL_ARRAY_BUFFER, positionBufferObject);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertexPositions2), &fNewData[0]);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
//Called to update the display.
//You should call glutSwapBuffers after all of your rendering to display what you rendered.
//If you need continuous updates of the screen, call glutPostRedisplay() at the end of the function.
void display() {
glUseProgram(theProgram);
float fXOffset = 0.0f, fYOffset = 0.0f;
ComputePositionOffsets(fXOffset, fYOffset);
AdjustVertexData(fXOffset, fYOffset);
//glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glRotatef(rotate_x, 1.0, 0.0, 0.0);
glRotatef(rotate_y, 0.0, 1.0, 0.0);
glBindBuffer(GL_ARRAY_BUFFER, positionBufferObject);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
GLubyte indices[] = { 0, 1, 2, 2, 3, 0, 4, 5, 6, 6, 7, 4, 8, 9, 10, 10, 11,
8, 12, 13, 14, 14, 15, 12, 16, 17, 18, 18, 19, 16, 20, 21, 22, 22,
23, 20 }; // back
glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_BYTE, indices);
glDisableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glFlush();
glUseProgram(0);
glutSwapBuffers();
}
//Called whenever the window is resized. The new window size is given, in pixels.
//This is an opportunity to call glViewport or glScissor to keep up with the change in size.
void reshape(int w, int h) {
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
}
//Called whenever a key on the keyboard was pressed.
//The key is given by the ''key'' parameter, which is in ASCII.
//It's often a good idea to have the escape key (ASCII value 27) call glutLeaveMainLoop() to
//exit the program.
void keyboard(unsigned char key, int x, int y) {
switch (key) {
case 27:
glutLeaveMainLoop();
return;
}
// Right arrow - increase rotation by 5 degree
if (key == GLUT_KEY_RIGHT) rotate_y += 5;
// Left arrow - decrease rotation by 5 degree
else if (key == GLUT_KEY_LEFT) rotate_y -= 5;
else if (key == GLUT_KEY_UP) rotate_x += 5;
else if (key == GLUT_KEY_DOWN) rotate_x -= 5;
// Request display update
glutPostRedisplay();
}
unsigned int defaults(unsigned int displayMode, int &width, int &height) {
return displayMode;
}
答案 0 :(得分：2)
const float vertexPositions2[] = {0.5,0.5,0.5,-0.5,0.5,0.5,-0.5,-0.5,0.5,0.5,-0.5,0.5,0.5,0.5,0.5,0.5,-0.5,0.5,0.5,0.5,0.5,0.5,0.5,-0.5,-0.5,0.5,-0.5,-0.5,0.5,0.5,-0.5,0.5,0.5,-0.5,0.5,-0.5,-0.5,-0.5,-0.5,-0.5,-0.5,0.5,-0.5,-0.5,-0.5,0.5,-0.5,-0.5,0.5,-0.5,0.5,-0.5,-0.5,0.5,0.5,-0.5,-0.5,-0.5,-0.5,-0.5,-0.5,0.5,-0.5,0.5,0.5,-0.5};
我猜这是一个组成立方体的3D矢量列表，因为在您的代码中使用了较低的24个（6个面* 4个角）索引，并且所有值都是0.5或-0.5。但是，您告诉OpenGL这是一个包含4个组件的向量列表，而不是3：
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
将第二个参数设置为4非常不寻常。如果将其设置为3，OpenGL会将w组件填入1。试试吧。如果你这样做，我想你会看到一个正方形。
除此之外，我没有在任何地方看到透视投影矩阵。如果没有，您将获得2D投影而不是3D投影。事情不会以你想要的方式出现。在实现旋转和移动之前，你会希望得到它。
以下这些行对您的程序没有任何影响，它们不属于现代图形程序。它们改变了固定函数矩阵堆栈中的矩阵，你不会（并且我认为不能，因为你使用的是GLSL 330）在着色器中使用矩阵。您必须自己将矩阵定义为统一变量。
glLoadIdentity();
glRotatef(rotate_x, 1.0, 0.0, 0.0);
glRotatef(rotate_y, 0.0, 1.0, 0.0);