OpenGL蓝宝书源码学习（六）第三章——Smoother.cpp

混合功能--抗锯齿源码示例(二维图形)

// Smoother.cpp
// OpenGL SuperBible
// Demonstrates point and line antialiasing
// Program by Richard S. Wright Jr.
#include 	// OpenGL toolkit
#include

#ifdef __APPLE__
#include
#else
#define FREEGLUT_STATIC
#include
#endif

GLShaderManager shaderManager;
GLFrustum viewFrustum;
GLBatch smallStarBatch;
GLBatch mediumStarBatch;
GLBatch largeStarBatch;
GLBatch mountainRangeBatch;
GLBatch moonBatch;

// Array of small stars
#define SMALL_STARS     100
#define MEDIUM_STARS     40
#define LARGE_STARS      15

#define SCREEN_X        800
#define SCREEN_Y        600

///////////////////////////////////////////////////////////////////////
// Reset flags as appropriate in response to menu selections
void ProcessMenu(int value)
{
switch(value)
{
case 1:
// Turn on antialiasing, and give hint to do the best
// job possible.
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glEnable(GL_POINT_SMOOTH);
glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
glEnable(GL_LINE_SMOOTH);
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
glEnable(GL_POLYGON_SMOOTH);
glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
break;

case 2:
// Turn off blending and all smoothing
glDisable(GL_BLEND);
glDisable(GL_LINE_SMOOTH);
glDisable(GL_POINT_SMOOTH);
break;

default:
break;
}

// Trigger a redraw
glutPostRedisplay();
}

///////////////////////////////////////////////////
// Called to draw scene
void RenderScene(void)
{
// Clear the window
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// Everything is white
GLfloat vWhite [] = { 1.0f, 1.0f, 1.0f, 1.0f };
shaderManager.UseStockShader(GLT_SHADER_FLAT, viewFrustum.GetProjectionMatrix(), vWhite);

// Draw small stars
glPointSize(1.0f);
smallStarBatch.Draw();

// Draw medium sized stars
glPointSize(4.0f);
mediumStarBatch.Draw();

// Draw largest stars
glPointSize(8.0f);
largeStarBatch.Draw();

// Draw the "moon"
moonBatch.Draw();

// Draw distant horizon
glLineWidth(3.5);
mountainRangeBatch.Draw();

moonBatch.Draw();

// Swap buffers
glutSwapBuffers();
}

// This function does any needed initialization on the rendering
// context.
void SetupRC()
{
M3DVector3f vVerts[SMALL_STARS];       // SMALL_STARS is the largest batch we are going to need
int i;

shaderManager.InitializeStockShaders();

// Populate star list
smallStarBatch.Begin(GL_POINTS, SMALL_STARS);
for(i = 0; i < SMALL_STARS; i++)
{
vVerts[i][0] = (GLfloat)(rand() % SCREEN_X);
vVerts[i][1] = (GLfloat)(rand() % (SCREEN_Y - 100)) + 100.0f;
vVerts[i][2] = 0.0f;
}
smallStarBatch.CopyVertexData3f(vVerts);
smallStarBatch.End();

// Populate star list
mediumStarBatch.Begin(GL_POINTS, MEDIUM_STARS);
for(i = 0; i < MEDIUM_STARS; i++)
{
vVerts[i][0] = (GLfloat)(rand() % SCREEN_X);
vVerts[i][1] = (GLfloat)(rand() % (SCREEN_Y - 100)) + 100.0f;
vVerts[i][2] = 0.0f;
}
mediumStarBatch.CopyVertexData3f(vVerts);
mediumStarBatch.End();

// Populate star list
largeStarBatch.Begin(GL_POINTS, LARGE_STARS);
for(i = 0; i < LARGE_STARS; i++)
{
vVerts[i][0] = (GLfloat)(rand() % SCREEN_X);
vVerts[i][1] = (GLfloat)(rand() % (SCREEN_Y - 100)) + 100.0f;
vVerts[i][2] = 0.0f;
}
largeStarBatch.CopyVertexData3f(vVerts);
largeStarBatch.End();

M3DVector3f vMountains[12] = { 0.0f, 25.0f, 0.0f,
50.0f, 100.0f, 0.0f,
100.0f, 25.0f, 0.0f,
225.0f, 125.0f, 0.0f,
300.0f, 50.0f, 0.0f,
375.0f, 100.0f, 0.0f,
460.0f, 25.0f, 0.0f,
525.0f, 100.0f, 0.0f,
600.0f, 20.0f, 0.0f,
675.0f, 70.0f, 0.0f,
750.0f, 25.0f, 0.0f,
800.0f, 90.0f, 0.0f };

mountainRangeBatch.Begin(GL_LINE_STRIP, 12);
mountainRangeBatch.CopyVertexData3f(vMountains);
mountainRangeBatch.End();

// The Moon
GLfloat x = 700.0f;     // Location and radius of moon
GLfloat y = 500.0f;
GLfloat r = 50.0f;
GLfloat angle = 0.0f;   // Another looping variable

moonBatch.Begin(GL_TRIANGLE_FAN, 34);
int nVerts = 0;
vVerts[nVerts][0] = x;
vVerts[nVerts][1] = y;
vVerts[nVerts][2] = 0.0f;
for(angle = 0; angle < 2.0f * 3.141592f; angle += 0.2f) {
nVerts++;
vVerts[nVerts][0] = x + float(cos(angle)) * r;
vVerts[nVerts][1] = y + float(sin(angle)) * r;
vVerts[nVerts][2] = 0.0f;
}
nVerts++;

vVerts[nVerts][0] = x + r;;
vVerts[nVerts][1] = y;
vVerts[nVerts][2] = 0.0f;
moonBatch.CopyVertexData3f(vVerts);
moonBatch.End();

// Black background
glClearColor(0.0f, 0.0f, 0.0f, 1.0f );
}

void ChangeSize(int w, int h)
{
// Prevent a divide by zero
if(h == 0)
h = 1;

// Set Viewport to window dimensions
glViewport(0, 0, w, h);

// Establish clipping volume (left, right, bottom, top, near, far)
viewFrustum.SetOrthographic(0.0f, SCREEN_X, 0.0f, SCREEN_Y, -1.0f, 1.0f);
}

int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(800, 600);
glutCreateWindow("Smoothing Out The Jaggies");

// Create the Menu
glutCreateMenu(ProcessMenu);
glutAddMenuEntry("Antialiased Rendering",1);
glutAddMenuEntry("Normal Rendering",2);
glutAttachMenu(GLUT_RIGHT_BUTTON);

glutReshapeFunc(ChangeSize);
glutDisplayFunc(RenderScene);

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

SetupRC();
glutMainLoop();

return 0;
}

源码解析：

2、void ChangeSize（int w，int h）

3、void RenderScene(void)

小结