gltut / Tut 05 Objects in Depth / VertexClipping.cpp

#include <string>
#include <vector>
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <glload/gl_3_3.h>
#include <GL/freeglut.h>
#include "../framework/framework.h"

#define ARRAY_COUNT( array ) (sizeof( array ) / (sizeof( array[0] ) * (sizeof( array ) != sizeof(void*) || sizeof( array[0] ) <= sizeof(void*))))

GLuint theProgram;

GLuint offsetUniform;
GLuint perspectiveMatrixUnif;

float perspectiveMatrix[16];
const float fFrustumScale = 1.0f;

void InitializeProgram()
{
	std::vector<GLuint> shaderList;

	shaderList.push_back(Framework::LoadShader(GL_VERTEX_SHADER, "Standard.vert"));
	shaderList.push_back(Framework::LoadShader(GL_FRAGMENT_SHADER, "Standard.frag"));

	theProgram = Framework::CreateProgram(shaderList);

	offsetUniform = glGetUniformLocation(theProgram, "offset");

	perspectiveMatrixUnif = glGetUniformLocation(theProgram, "perspectiveMatrix");

	float fzNear = 1.0f; float fzFar = 3.0f;

	memset(perspectiveMatrix, 0, sizeof(float) * 16);

	perspectiveMatrix[0] = fFrustumScale;
	perspectiveMatrix[5] = fFrustumScale;
	perspectiveMatrix[10] = (fzFar + fzNear) / (fzNear - fzFar);
	perspectiveMatrix[14] = (2 * fzFar * fzNear) / (fzNear - fzFar);
	perspectiveMatrix[11] = -1.0f;

	glUseProgram(theProgram);
	glUniformMatrix4fv(perspectiveMatrixUnif, 1, GL_FALSE, perspectiveMatrix);
	glUseProgram(0);
}

const int numberOfVertices = 36;

#define RIGHT_EXTENT 0.8f
#define LEFT_EXTENT -RIGHT_EXTENT
#define TOP_EXTENT 0.20f
#define MIDDLE_EXTENT 0.0f
#define BOTTOM_EXTENT -TOP_EXTENT
#define FRONT_EXTENT -1.25f
#define REAR_EXTENT -1.75f

#define GREEN_COLOR 0.75f, 0.75f, 1.0f, 1.0f
#define BLUE_COLOR 	0.0f, 0.5f, 0.0f, 1.0f
#define RED_COLOR 1.0f, 0.0f, 0.0f, 1.0f
#define GREY_COLOR 0.8f, 0.8f, 0.8f, 1.0f
#define BROWN_COLOR 0.5f, 0.5f, 0.0f, 1.0f

const float vertexData[] = {
	//Object 1 positions
	LEFT_EXTENT,	TOP_EXTENT,		REAR_EXTENT,
	LEFT_EXTENT,	MIDDLE_EXTENT,	FRONT_EXTENT,
	RIGHT_EXTENT,	MIDDLE_EXTENT,	FRONT_EXTENT,
	RIGHT_EXTENT,	TOP_EXTENT,		REAR_EXTENT,

	LEFT_EXTENT,	BOTTOM_EXTENT,	REAR_EXTENT,
	LEFT_EXTENT,	MIDDLE_EXTENT,	FRONT_EXTENT,
	RIGHT_EXTENT,	MIDDLE_EXTENT,	FRONT_EXTENT,
	RIGHT_EXTENT,	BOTTOM_EXTENT,	REAR_EXTENT,

	LEFT_EXTENT,	TOP_EXTENT,		REAR_EXTENT,
	LEFT_EXTENT,	MIDDLE_EXTENT,	FRONT_EXTENT,
	LEFT_EXTENT,	BOTTOM_EXTENT,	REAR_EXTENT,

	RIGHT_EXTENT,	TOP_EXTENT,		REAR_EXTENT,
	RIGHT_EXTENT,	MIDDLE_EXTENT,	FRONT_EXTENT,
	RIGHT_EXTENT,	BOTTOM_EXTENT,	REAR_EXTENT,

	LEFT_EXTENT,	BOTTOM_EXTENT,	REAR_EXTENT,
	LEFT_EXTENT,	TOP_EXTENT,		REAR_EXTENT,
	RIGHT_EXTENT,	TOP_EXTENT,		REAR_EXTENT,
	RIGHT_EXTENT,	BOTTOM_EXTENT,	REAR_EXTENT,

	//	0, 2, 1,
	//	3, 2, 0,

	//Object 2 positions
	TOP_EXTENT,		RIGHT_EXTENT,	REAR_EXTENT,
	MIDDLE_EXTENT,	RIGHT_EXTENT,	FRONT_EXTENT,
	MIDDLE_EXTENT,	LEFT_EXTENT,	FRONT_EXTENT,
	TOP_EXTENT,		LEFT_EXTENT,	REAR_EXTENT,

	BOTTOM_EXTENT,	RIGHT_EXTENT,	REAR_EXTENT,
	MIDDLE_EXTENT,	RIGHT_EXTENT,	FRONT_EXTENT,
	MIDDLE_EXTENT,	LEFT_EXTENT,	FRONT_EXTENT,
	BOTTOM_EXTENT,	LEFT_EXTENT,	REAR_EXTENT,

	TOP_EXTENT,		RIGHT_EXTENT,	REAR_EXTENT,
	MIDDLE_EXTENT,	RIGHT_EXTENT,	FRONT_EXTENT,
	BOTTOM_EXTENT,	RIGHT_EXTENT,	REAR_EXTENT,

	TOP_EXTENT,		LEFT_EXTENT,	REAR_EXTENT,
	MIDDLE_EXTENT,	LEFT_EXTENT,	FRONT_EXTENT,
	BOTTOM_EXTENT,	LEFT_EXTENT,	REAR_EXTENT,

	BOTTOM_EXTENT,	RIGHT_EXTENT,	REAR_EXTENT,
	TOP_EXTENT,		RIGHT_EXTENT,	REAR_EXTENT,
	TOP_EXTENT,		LEFT_EXTENT,	REAR_EXTENT,
	BOTTOM_EXTENT,	LEFT_EXTENT,	REAR_EXTENT,

	//Object 1 colors
	GREEN_COLOR,
	GREEN_COLOR,
	GREEN_COLOR,
	GREEN_COLOR,

	BLUE_COLOR,
	BLUE_COLOR,
	BLUE_COLOR,
	BLUE_COLOR,

	RED_COLOR,
	RED_COLOR,
	RED_COLOR,

	GREY_COLOR,
	GREY_COLOR,
	GREY_COLOR,

	BROWN_COLOR,
	BROWN_COLOR,
	BROWN_COLOR,
	BROWN_COLOR,

	//Object 2 colors
	RED_COLOR,
	RED_COLOR,
	RED_COLOR,
	RED_COLOR,

	BROWN_COLOR,
	BROWN_COLOR,
	BROWN_COLOR,
	BROWN_COLOR,

	BLUE_COLOR,
	BLUE_COLOR,
	BLUE_COLOR,

	GREEN_COLOR,
	GREEN_COLOR,
	GREEN_COLOR,

	GREY_COLOR,
	GREY_COLOR,
	GREY_COLOR,
	GREY_COLOR,
};

const GLshort indexData[] =
{
	0, 2, 1,
	3, 2, 0,

	4, 5, 6,
	6, 7, 4,

	8, 9, 10,
	11, 13, 12,

	14, 16, 15,
	17, 16, 14,
};

GLuint vertexBufferObject;
GLuint indexBufferObject;
GLuint vao;


void InitializeVertexBuffer()
{
	glGenBuffers(1, &vertexBufferObject);

	glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObject);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW);
	glBindBuffer(GL_ARRAY_BUFFER, 0);

	glGenBuffers(1, &indexBufferObject);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferObject);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indexData), indexData, GL_STATIC_DRAW);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}

//Called after the window and OpenGL are initialized. Called exactly once, before the main loop.
void init()
{
	InitializeProgram();
	InitializeVertexBuffer();

	glGenVertexArrays(1, &vao);
	glBindVertexArray(vao);

	size_t colorDataOffset = sizeof(float) * 3 * numberOfVertices;
	glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObject);
	glEnableVertexAttribArray(0);
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
	glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, (void*)colorDataOffset);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBufferObject);

	glBindVertexArray(0);

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

	glEnable(GL_DEPTH_TEST);
	glDepthMask(GL_TRUE);
	glDepthFunc(GL_LESS);
	glDepthRange(0.0f, 1.0f);
}

//Called to update the display.
//You should call glutSwapBuffers after all of your rendering to display what you rendered.
//If you need continuous updates of the screen, call glutPostRedisplay() at the end of the function.
void display()
{
	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	glClearDepth(1.0f);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glUseProgram(theProgram);
	glBindVertexArray(vao);

	glUniform3f(offsetUniform, 0.0f, 0.0f, 0.5f);
	glDrawElements(GL_TRIANGLES, ARRAY_COUNT(indexData), GL_UNSIGNED_SHORT, 0);

	glUniform3f(offsetUniform, 0.0f, 0.0f, -1.0f);
	glDrawElementsBaseVertex(GL_TRIANGLES, ARRAY_COUNT(indexData),
		GL_UNSIGNED_SHORT, 0, numberOfVertices / 2);

	glBindVertexArray(0);
	glUseProgram(0);

	glutSwapBuffers();
}

//Called whenever the window is resized. The new window size is given, in pixels.
//This is an opportunity to call glViewport or glScissor to keep up with the change in size.
void reshape (int w, int h)
{
	perspectiveMatrix[0] = fFrustumScale * (h / (float)w);
	perspectiveMatrix[5] = fFrustumScale;

	glUseProgram(theProgram);
	glUniformMatrix4fv(perspectiveMatrixUnif, 1, GL_FALSE, perspectiveMatrix);
	glUseProgram(0);

	glViewport(0, 0, (GLsizei) w, (GLsizei) h);
}

//Called whenever a key on the keyboard was pressed.
//The key is given by the ''key'' parameter, which is in ASCII.
//It's often a good idea to have the escape key (ASCII value 27) call glutLeaveMainLoop() to 
//exit the program.
void keyboard(unsigned char key, int x, int y)
{
	switch (key)
	{
	case 27:
		glutLeaveMainLoop();
		break;
	}
}


unsigned int defaults(unsigned int displayMode, int &width, int &height) {return displayMode;}
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