OPENGL超级宝典-6.6

最新推荐文章于 2020-11-25 15:10:04 发布

Golden_Shadow

最新推荐文章于 2020-11-25 15:10:04 发布

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分类专栏：图形学

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本文分享了一段OpenGL着色器的学习代码实例，通过绘制旋转的环面来演示如何使用顶点和片段着色器。文章涉及GLSL语言的基础用法、矩阵变换以及基本的OpenGL环境设置。

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开始学习着色器了,果然跟固定流水线不同.好在前一段数学知识学得好,运用到这里学得不吃力.下面这段代码,我解释不出太多,学到差不多的时候再总结一下吧.渐渐开窍的感觉,先广度优先吧.

#include "stdafx.h"
#include <GLTools.h>
#include <GLMatrixStack.h>
#include <GLFrame.h>
#include <GLFrustum.h>
#include <GLGeometryTransform.h>
#include <StopWatch.h>

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

GLFrame viewFrame;
GLFrustum viewFrustum;
GLTriangleBatch torusBatch;
GLMatrixStack modelViewMatrix;
GLMatrixStack projectionMatrix;
GLGeometryTransform transformPipeline;

GLuint	flatShader;

GLint	locMVP;
GLint   locColor;

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

	glEnable(GL_DEPTH_TEST);
	glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

    viewFrame.MoveForward(4.0f);

    gltMakeTorus(torusBatch, .80f, 0.25f, 52, 26);

	flatShader = gltLoadShaderPairWithAttributes("FlatShader.vp", "FlatShader.fp", 1, GLT_ATTRIBUTE_VERTEX, "vVertex");

	locMVP = glGetUniformLocation(flatShader, "mvpMatrix");
	locColor = glGetUniformLocation(flatShader, "vColorValue");
}

void ShutdownRC(void)
{

}

void RenderScene(void)
{
	static CStopWatch rotTimer;

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		
    modelViewMatrix.PushMatrix(viewFrame);
	modelViewMatrix.Rotate(rotTimer.GetElapsedSeconds() * 10.0f, 0.0f, 1.0f, 0.0f);
	
	GLfloat vColor[] = { 0.1f, 0.1f, 1.f, 1.0f };

	glUseProgram(flatShader);
	glUniform4fv(locColor, 1, vColor);
	glUniformMatrix4fv(locMVP, 1, GL_FALSE, transformPipeline.GetModelViewProjectionMatrix());
    torusBatch.Draw();

    modelViewMatrix.PopMatrix();

    glutSwapBuffers();
	glutPostRedisplay();
}

void ChangeSize(int w, int h)
{
	if(h == 0)
		h = 1;

    glViewport(0, 0, w, h);

    viewFrustum.SetPerspective(35.0f, float(w)/float(h), 1.0f, 100.0f);
    
    projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix());
    transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix);
}

int main(int argc, char* argv[])
{
	gltSetWorkingDirectory(argv[0]);
	
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
	glutInitWindowSize(800, 600);
	glutCreateWindow("Simple Transformed Geometry");
    glutReshapeFunc(ChangeSize);
    glutDisplayFunc(RenderScene);

	GLenum err = glewInit();
	if (GLEW_OK != err) {
		fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
		return 1;
    }
	
	SetupRC();
	glutMainLoop();
	ShutdownRC();
	return 0;
}