GLSL 透视变换（着色器实现C语言）

时间：2014-02-16 01:53:58 阅读：604 评论：0 收藏：0 [点我收藏+]

shader

perspective.vert

#version 330

layout(location =0) in vec4 vertexPosition;
layout(location =1) in vec4 vertexColor;

smooth out vec4 vColor;

uniform vec2 offset;
uniform float zNear;
uniform float zFar;
uniform float frustumScale;

void main()
{
	vec4 cameraPosition =vertexPosition +vec4(offset.x, offset.y, 0.0, 0.0);
	vec4 clipPosition;

	clipPosition.xy =cameraPosition.xy *frustumScale;

	clipPosition.z =cameraPosition.z*(zNear +zFar)/(zNear -zFar);
	clipPosition.z +=2 *zNear*zFar /(zNear -zFar);

	clipPosition.w =-cameraPosition.z;

	gl_Position =clipPosition;
	vColor =vertexColor;
}

perspective.frag

#version 330

smooth in vec4 vColor;

out vec4 outputColor;

void main()
{
	outputColor =vColor;
}

perspective.c

#include <stdio.h>
#include <stdlib.h>
#include <GL/glew.h>
#include "readtext.h"

#ifdef _APPLE_
#include <glut/glut.h>
#else  
#define FREEGLUT_STATIC 
#include <GL/glut.h> 
#endif 

#pragma comment(lib, "readtext.lib")
#pragma comment(lib, "glew32.lib")


GLuint vShader, fShader, programHandle;

GLint vaoHandle, vboHandles[2], positionBufferHandle, colorBufferHandle;

GLuint offsetLocation, zNearLocation, zFarLocation, frustumLocation;


//////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
int infoLogLength =0;
int charWritten =0;
char *infoLog;

///////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////
float positionData[] ={ 
	0.25f,  0.25f, -1.25f, 1.0f,
	 0.25f, -0.25f, -1.25f, 1.0f,
	-0.25f,  0.25f, -1.25f, 1.0f,

	 0.25f, -0.25f, -1.25f, 1.0f,
	-0.25f, -0.25f, -1.25f, 1.0f,
	-0.25f,  0.25f, -1.25f, 1.0f,

	 0.25f,  0.25f, -2.75f, 1.0f,
	-0.25f,  0.25f, -2.75f, 1.0f,
	 0.25f, -0.25f, -2.75f, 1.0f,

	 0.25f, -0.25f, -2.75f, 1.0f,
	-0.25f,  0.25f, -2.75f, 1.0f,
	-0.25f, -0.25f, -2.75f, 1.0f,

	-0.25f,  0.25f, -1.25f, 1.0f,
	-0.25f, -0.25f, -1.25f, 1.0f,
	-0.25f, -0.25f, -2.75f, 1.0f,

	-0.25f,  0.25f, -1.25f, 1.0f,
	-0.25f, -0.25f, -2.75f, 1.0f,
	-0.25f,  0.25f, -2.75f, 1.0f,

	 0.25f,  0.25f, -1.25f, 1.0f,
	 0.25f, -0.25f, -2.75f, 1.0f,
	 0.25f, -0.25f, -1.25f, 1.0f,

	 0.25f,  0.25f, -1.25f, 1.0f,
	 0.25f,  0.25f, -2.75f, 1.0f,
	 0.25f, -0.25f, -2.75f, 1.0f,

	 0.25f,  0.25f, -2.75f, 1.0f,
	 0.25f,  0.25f, -1.25f, 1.0f,
	-0.25f,  0.25f, -1.25f, 1.0f,

	 0.25f,  0.25f, -2.75f, 1.0f,
	-0.25f,  0.25f, -1.25f, 1.0f,
	-0.25f,  0.25f, -2.75f, 1.0f,

	 0.25f, -0.25f, -2.75f, 1.0f,
	-0.25f, -0.25f, -1.25f, 1.0f,
	 0.25f, -0.25f, -1.25f, 1.0f,

	 0.25f, -0.25f, -2.75f, 1.0f,
	-0.25f, -0.25f, -2.75f, 1.0f,
	-0.25f, -0.25f, -1.25f, 1.0f};

float colorData[] ={
	0.0f, 0.0f, 1.0f, 1.0f,
	0.0f, 0.0f, 1.0f, 1.0f,
	0.0f, 0.0f, 1.0f, 1.0f,

	0.0f, 0.0f, 1.0f, 1.0f,
	0.0f, 0.0f, 1.0f, 1.0f,
	0.0f, 0.0f, 1.0f, 1.0f,

	0.8f, 0.8f, 0.8f, 1.0f,
	0.8f, 0.8f, 0.8f, 1.0f,
	0.8f, 0.8f, 0.8f, 1.0f,

	0.8f, 0.8f, 0.8f, 1.0f,
	0.8f, 0.8f, 0.8f, 1.0f,
	0.8f, 0.8f, 0.8f, 1.0f,

	0.0f, 1.0f, 0.0f, 1.0f,
	0.0f, 1.0f, 0.0f, 1.0f,
	0.0f, 1.0f, 0.0f, 1.0f,

	0.0f, 1.0f, 0.0f, 1.0f,
	0.0f, 1.0f, 0.0f, 1.0f,
	0.0f, 1.0f, 0.0f, 1.0f,

	0.5f, 0.5f, 0.0f, 1.0f,
	0.5f, 0.5f, 0.0f, 1.0f,
	0.5f, 0.5f, 0.0f, 1.0f,

	0.5f, 0.5f, 0.0f, 1.0f,
	0.5f, 0.5f, 0.0f, 1.0f,
	0.5f, 0.5f, 0.0f, 1.0f,

	1.0f, 0.0f, 0.0f, 1.0f,
	1.0f, 0.0f, 0.0f, 1.0f,
	1.0f, 0.0f, 0.0f, 1.0f,

	1.0f, 0.0f, 0.0f, 1.0f,
	1.0f, 0.0f, 0.0f, 1.0f,
	1.0f, 0.0f, 0.0f, 1.0f,

	0.0f, 1.0f, 1.0f, 1.0f,
	0.0f, 1.0f, 1.0f, 1.0f,
	0.0f, 1.0f, 1.0f, 1.0f,

	0.0f, 1.0f, 1.0f, 1.0f,
	0.0f, 1.0f, 1.0f, 1.0f,
	0.0f, 1.0f, 1.0f, 1.0f};


void SetupShader()
{
	char *renderer;
	char *vender;
	char *version;
	char *glslVersion;
	//////////////////////
	char *vs, *fs;
	char *vv, *ff;
	//////////////////////
	renderer =glGetString(GL_RENDERER);
	vender =glGetString(GL_VENDOR);
	version =glGetString(GL_VERSION);
	glslVersion =glGetString(GL_SHADING_LANGUAGE_VERSION);

	printf("*****************************************************\n");
	printf("graphic card:\t%s \n", renderer);
	printf("graphic company:\t%s \n", vender);
	printf("openGL version:\t%s \n", version);
	printf("GLSL version:\t %s \n", glslVersion);
	printf("*****************************************************\n");
	///////////////////////////////////////////////////////////////////////
	vShader =glCreateShader(GL_VERTEX_SHADER);

	vs =readText("shader/perspective.vert");
	//printf("%s\n",vs);
	vv =vs;

	if(vShader ==0)
	{
		printf("Error: fail to create shader!");
		exit(1);
	}

	glShaderSource(vShader, 1, &vv, NULL);
	glCompileShader(vShader);
	free(vs);

	glGetShaderiv(vShader, GL_INFO_LOG_LENGTH, &infoLogLength);
	if(infoLogLength >0)
	{
		infoLog =(char *)malloc(infoLogLength);
		glGetShaderInfoLog(vShader, infoLogLength, &charWritten, infoLog);
		printf("%s\n",infoLog);
		printf("********************************************************************\n");
		free(infoLog);
	}
	///////////////////////////////////////////////////////////////////////////
	fShader =glCreateShader(GL_FRAGMENT_SHADER);
	if(fShader ==0)
	{
		printf("can‘t create fragment shader! \n");
		exit(1);
	}
    
	fs =readText("shader/perspective.frag");
    //printf("%s \n",fs);
	ff= fs;
	glShaderSource(fShader, 1, &ff, NULL);
	glCompileShader(fShader);
	free(fs);

	glGetShaderiv(fShader, GL_INFO_LOG_LENGTH, &infoLogLength);

	if(infoLogLength >0)
	{
		infoLog =(char *)malloc(infoLogLength);
		glGetShaderInfoLog(fShader, infoLogLength, &charWritten, infoLog);
		////////charWritten is 
		printf("%s \n",infoLog);
		printf("*********************************************************\n");
		free(infoLog);
	}
	///////////////////////////////////////////////
	////////////////////////////////////////
	programHandle =glCreateProgram();

	glAttachShader(programHandle, vShader);
	glAttachShader(programHandle, fShader);

	glLinkProgram(programHandle);
	glUseProgram(programHandle);
	
	glGetProgramiv(programHandle, GL_INFO_LOG_LENGTH, &infoLogLength);
	if(infoLogLength >0)
	{
		infoLog =(char *)malloc(infoLogLength);
		glGetProgramInfoLog(programHandle, infoLogLength, &charWritten, infoLog);
		printf("%s \n", infoLog);
		printf("*********************************************************\n");
		free(infoLog);
	}	

}

void InitVBO()
{
	glGenBuffers(2, vboHandles);
	positionBufferHandle =vboHandles[0];
	colorBufferHandle =vboHandles[1];
	///////////////////////////////////////////
	glBindBuffer(GL_ARRAY_BUFFER, positionBufferHandle);
	glBufferData(GL_ARRAY_BUFFER, sizeof(positionData), positionData, GL_STATIC_DRAW);

	glBindBuffer(GL_ARRAY_BUFFER, colorBufferHandle);
	glBufferData(GL_ARRAY_BUFFER, sizeof(colorData), colorData, GL_STATIC_DRAW);
	/////////////////////////////////////////
	glGenVertexArrays(1, &vaoHandle);
	glBindVertexArray(vaoHandle);
	//////////////////////////////////////
	glEnableVertexAttribArray(0);
	glEnableVertexAttribArray(1);

	glBindBuffer(GL_ARRAY_BUFFER, positionBufferHandle);
	glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, NULL);

	glBindBuffer(GL_ARRAY_BUFFER, colorBufferHandle);
	glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, NULL);
}

////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////
void SetupRC()
{
	glewInit();

	SetupShader();

	InitVBO();

	glClearColor(1.0, 0.0, 0.0, 1.0);

	////////////////////////////////////////
	glEnable(GL_CULL_FACE);
	glCullFace(GL_BACK);
	glFrontFace(GL_CW);
}



void RenderScene()
{
	glClear(GL_COLOR_BUFFER_BIT);
	glUseProgram(programHandle);

	offsetLocation =glGetUniformLocation(programHandle, "offset");
	zNearLocation =glGetUniformLocation(programHandle, "zNear");
	zFarLocation =glGetUniformLocation(programHandle, "zFar");
	frustumLocation =glGetUniformLocation(programHandle, "frustumScale");

	glUniform2f(offsetLocation, 0.5, 0.5);
	glUniform1f(zNearLocation, 1.0f);
	glUniform1f(zFarLocation, 3.0f);
	glUniform1f(frustumLocation, 1.0f);

	glBindVertexArray(vaoHandle);
	glDrawArrays(GL_TRIANGLES, 0, 36);
	glBindVertexArray(0);




	glutSwapBuffers();
	glutPostRedisplay();
}



void keyBoard(unsigned char key, int x, int y)
{
	if(key ==GLUT_KEY_F1)
		exit(0);
}




int main(int argc, char *argv[])
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE |GLUT_RGBA |GLUT_DEPTH);

	glutInitWindowSize(800, 600);
	glutInitWindowPosition(0, 0);
	glutCreateWindow("fourth :perspective ");

	SetupRC();
	glutDisplayFunc(RenderScene);

	glutSpecialFunc(keyBoard);
	glutMainLoop();
	return 0;
}

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GLSL 透视变换（着色器实现C语言）

原文：http://blog.csdn.net/lelieven/article/details/19242955

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