frame buffer object, color buffer, depth buffer

FBO, color buffer, depth buffer를 사용하는 프로젝트이다. FBO 등에 관한 설명은 생략한다.

회전하는 teapot을 회전하는 정육면체의 각 면에 color buffer와 depth buffer를 사용해서 그린다.

#include 
#include 
#include "glext.h"

const int window_height = 380, window_width = 630, tex_height = 512, tex_width = 512;
GLuint fboId = 1, texId = 0, drbId = 0;
GLfloat xRotated, yRotated, zRotated, rot = 0.0;

double cubePos = -6.0;
static GLfloat cubeVertices[26][3] = {
	// Front face
	{-1,-1,1}, {1,-1,1}, {-1,1,1}, {1,1,1},
	// Right face
	{1,1,1}, {1,-1,1}, {1,1,-1}, {1,-1,-1},
	// Back face
	{1,-1,-1}, {-1,-1,-1}, {1, 1, -1}, {-1, 1, -1},
	// Left face
	{-1,1,-1}, {-1,-1,-1}, {-1,1,1}, {-1,-1,1},
	// Bottom face
	{-1,-1,1}, {-1,-1,-1}, {1,-1,1},{1,-1,-1},
	// move to top
	{1,-1,-1}, {-1,1,1},
	// Top Face
	{-1,1,1}, {1,1,1}, {-1,1,-1}, {1,1,-1}
};
void drawf1f3f5() {
	glBegin(GL_TRIANGLES);
	// front face
	glNormal3f(0, 0, 1);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[3]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[2]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[0]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[0]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[1]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[3]);

	// right face
	glNormal3f(1, 0, 0);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[4]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[5]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[7]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[7]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[6]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[4]);

	// top face
	glNormal3f(0, 1, 0);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[23]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[25]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[24]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[24]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[22]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[23]);
	glEnd();
}
void drawf2f4f6() {
	glBegin(GL_TRIANGLES);
	// left face
	glNormal3f(-1, 0, 0);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[14]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[12]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[13]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[13]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[15]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[14]);

	// bottom face
	glNormal3f(0, -1, 0);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[17]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[19]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[18]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[18]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[16]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[17]);

	// back face
	glNormal3f(0, 0, -1);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[8]);
	glTexCoord2f(1, 0);  glVertex3fv(cubeVertices[9]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[11]);
	glTexCoord2f(1, 1);  glVertex3fv(cubeVertices[11]);
	glTexCoord2f(0, 1);  glVertex3fv(cubeVertices[10]);
	glTexCoord2f(0, 0);  glVertex3fv(cubeVertices[8]);
	glEnd();
}
void draw() {
	drawf1f3f5();
	drawf2f4f6();
}
void display(void)
{
	float angle = rot;

	// go to texture viewport (render to texture)
	glViewport(0, 0, tex_width, tex_height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60.0f, tex_width / (double)tex_height, 1.0f, 100.0f);
	glMatrixMode(GL_MODELVIEW);

	glLoadIdentity();
	glTranslatef(0, 0, cubePos);

	//bind FBO and clear buffer
	glBindFramebuffer(GL_FRAMEBUFFER, fboId);
	glClearColor(1, 1, 1, 1);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	{
		glPushMatrix();
		glRotatef(angle*0.5f, 1, 0, 0);
		glRotatef(angle, 0, 1, 0);
		glRotatef(angle*0.7f, 0, 0, 1);
		glColor3f(1, 0, 0);
		glutSolidTeapot(1);
		glPopMatrix();
	}

	// unbind
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	//clear default buffer
	glClearColor(0, 0, 0, 0);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

	//go to normal viewport
	glViewport(0, 0, window_width, window_height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60.0f, (double)(window_width) / (double)window_height, 1.0f, 100.0f);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

	//draw left side cube, used only color buffer (texId)
	{
		glPushMatrix();
		glTranslatef(-2.0, 0, cubePos);
		glRotatef(xRotated, 1, 0, 0);
		glRotatef(yRotated, 0, 1, 0);
		glBindTexture(GL_TEXTURE_2D, texId);
		glColor4f(1, 1, 1, 1);
		draw();
		glBindTexture(GL_TEXTURE_2D, 0);
		glPopMatrix();
	}

	//draw part of center cube, used color buffer (texId)
	{
		glPushMatrix();
		glTranslatef(0, 1.5, cubePos);
		glRotatef(xRotated, 1, 0, 0);
		glRotatef(yRotated, 0, 1, 0);
		glBindTexture(GL_TEXTURE_2D, texId);
		glColor4f(1, 1, 1, 1);
		drawf1f3f5();
		glBindTexture(GL_TEXTURE_2D, 0);
		glPopMatrix();
	}


	//go to normal viewport
	glEnable(GL_TEXTURE_2D);
	glViewport(0, 0, window_width, window_height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(60.0f, (double)(window_width) / (double)window_height, 1.0f, 100.0f);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

	//draw right side cube, used only depth buffer (drbId)
	{
		glPushMatrix();
		glTranslatef(2.0, 0, cubePos);
		glRotatef(xRotated, 1, 0, 0);
		glRotatef(yRotated, 0, 1, 0);
		glBindTexture(GL_TEXTURE_2D, drbId);
		glColor3f(1, 0, 0);
		draw();
		glBindTexture(GL_TEXTURE_2D, 0);
		glPopMatrix();
	}

	//draw rest of center cube, used depth buffer
	{
		glPushMatrix();
		glTranslatef(0, 1.5, cubePos);
		glRotatef(xRotated, 1, 0, 0);
		glRotatef(yRotated, 0, 1, 0);
		glBindTexture(GL_TEXTURE_2D, drbId);
		glColor4f(1, 1, 1, 1);
		drawf2f4f6();
		glBindTexture(GL_TEXTURE_2D, 0);
		glPopMatrix();
	}

	glutSwapBuffers();
}

void idle()
{
	yRotated += 0.5;
	xRotated += 1.0;
	rot += 1.0;
	glutPostRedisplay();
}


int main(int argc, char **argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(window_width, window_height);
	glutCreateWindow("OpenGL Sample 02");
	
	glutDisplayFunc(display);
	glutIdleFunc(idle);

	
	glShadeModel(GL_SMOOTH);                    // shading mathod: GL_SMOOTH or GL_FLAT
	glPixelStorei(GL_UNPACK_ALIGNMENT, 4);      // 4-byte pixel alignment
	
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
	glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
	glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
	glEnable(GL_DEPTH_TEST);
	glEnable(GL_LIGHTING);
	glEnable(GL_TEXTURE_2D);
	glDisable(GL_CULL_FACE);

	glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
	glEnable(GL_COLOR_MATERIAL);

	glClearColor(0, 0, 0, 0);                   // background color
	glClearStencil(0);                          // clear stencil buffer
	glClearDepth(1.0f);                         // 0 is near, 1 is far
	glDepthFunc(GL_LEQUAL);


	//lights
	GLfloat lightKa[] = { .2f, .2f, .2f, 1.0f };  //ambient light
	GLfloat lightKd[] = { .7f, .7f, .7f, 1.0f };  //diffuse light
	GLfloat lightKs[] = { 1, 1, 1, 1 };           //specular light
	glLightfv(GL_LIGHT0, GL_AMBIENT, lightKa);
	glLightfv(GL_LIGHT0, GL_DIFFUSE, lightKd);
	glLightfv(GL_LIGHT0, GL_SPECULAR, lightKs);

	float lightPos[4] = { 0, 0, 20, 1 };
	glLightfv(GL_LIGHT0, GL_POSITION, lightPos);

	glEnable(GL_LIGHT0);



	//framebuffer object
	glGenFramebuffers(1, &fboId);
	glBindFramebuffer(GL_FRAMEBUFFER, fboId);

	//color buffer
	glGenTextures(1, &texId);
	glBindTexture(GL_TEXTURE_2D, texId);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex_width, tex_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);

	glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texId, 0);


	//depth buffer
	glBindFramebuffer(GL_FRAMEBUFFER, fboId);
	glGenTextures(1, &drbId);
	glBindTexture(GL_TEXTURE_2D, drbId);

	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	int level = 0;
	glTexImage2D(GL_TEXTURE_2D, level, GL_DEPTH_COMPONENT, tex_width, tex_height, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0);
	glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, drbId, level);

	//unbind
	glBindTexture(GL_TEXTURE_2D, 0);
	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	glutMainLoop();
	return 0;
}