【OpenGL】蓝宝书2-3 Bounce 源码示例

//#pragma comment(lib,"gltools.lib")

#include <GLTools.h>
#include <GLShaderManager.h>

#define FREEGLUT_STATIC
#include <gl/glut.h>
#include <gl/glew.h>

GLBatch squareBatch;
GLShaderManager shaderManager;

GLfloat blockSize = 0.1f;
GLfloat vVerts[] = { -blockSize - 0.5f, -blockSize, 0.0f,
					 blockSize - 0.5f, -blockSize, 0.0f,
					blockSize - 0.5f, blockSize, 0.0f,
					-blockSize - 0.5f, blockSize, 0.0f };

void SetupRC()
{
	glClearColor(0.0f, 0.0f, 1.0f, 1.0f);

	shaderManager.InitializeStockShaders();

	squareBatch.Begin(GL_TRIANGLE_FAN, 4);
	squareBatch.CopyVertexData3f(vVerts);
	squareBatch.End();
}

void BounceFunction(void)
{
	static GLfloat xDir = 1.0f;
	static GLfloat yDir = 1.0f;
	
	GLfloat stepSize = 0.005f;


	GLfloat blockX = vVerts[0]; //最左边X
	GLfloat blockY = vVerts[7]; //最上边Y

	blockY += stepSize * yDir;
	blockX += stepSize * xDir;

	if (blockX < -1.0f) { blockX = -1.0f; xDir *= -1.0f; }
	if (blockX > (1.0 - blockSize * 2)) { blockX = 1.0 - blockSize * 2; xDir *= -1.0f; }
	if (blockY < -1.0f + blockSize * 2) { blockY = -1.0f + blockSize * 2; yDir *= -1.0f; }
	if (blockY > 1.0f) { blockY = 1.0f; yDir *= -1.0f; }

	vVerts[0] = blockX;
	vVerts[1] = blockY - blockSize * 2;

	vVerts[3] = blockX + blockSize * 2;
	vVerts[4] = blockY - blockSize * 2;

	vVerts[6] = blockX + blockSize * 2;
	vVerts[7] = blockY;

	vVerts[9] = blockX;
	vVerts[10] = blockY;

	squareBatch.CopyVertexData3f(vVerts);
}

void RenderScene(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

	GLfloat vRed[] = { 1.0f, 0.0f, 0.0f, 1.0f };
	shaderManager.UseStockShader(GLT_SHADER_IDENTITY, vRed);
	squareBatch.Draw();

	//交换缓冲区内容 刷新
	glutSwapBuffers();

	//修改数据
	BounceFunction();
	//重绘
	glutPostRedisplay();
}

void ChangeSize(int w, int h) {
	glViewport(0, 0, w, h);
}

int main(int argc, char* argv[])
{
	gltSetWorkingDirectory(argv[0]);

	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH);
	glutInitWindowSize(800, 600);
	glutCreateWindow("Bouncing block");

	GLenum err = glewInit();
	if (GLEW_OK != err) {
		fprintf(stderr, "Error:%s\n", glewGetErrorString(err));
		return 1;
	}

	glutReshapeFunc(ChangeSize);
	glutDisplayFunc(RenderScene);
	
	SetupRC();

	glutMainLoop();
	return 0;
}

gltools.lib的引入可如下给项目配置即可 （如果懒得这么操作可以写 #pragma comment(lib,"gltools.lib") 在代码最顶部