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@roxlu
Created May 24, 2012 07:36
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Basic bare bones openGL with openFrameworks (VBO, VAO, SHADER and texture(s))
#include "testApp.h"
//--------------------------------------------------------------
void testApp::setup(){
ofEnableNormalizedTexCoords();
ofDisableArbTex();
ofSetFrameRate(60);
ofBackground(22,33,44);
// Shader + VAO/VBO
// -----------------
// create shader program
shader.setupShaderFromSource(GL_VERTEX_SHADER, VS);
shader.setupShaderFromSource(GL_FRAGMENT_SHADER, FS);
shader.linkProgram();
GLint pos_attrib = glGetAttribLocation(shader.getProgram(), "pos");
GLint tex_attrib = glGetAttribLocation(shader.getProgram(), "tex");
printf("TEX: %d\n", tex_attrib);
// setup matrices to replace GL_MODELVIEW and GL_PROJECTION
view_matrix.translate(0.0f,0.0f,-10.0f);
projection_matrix.makePerspectiveMatrix(65.0f, ofGetWidth()/ofGetHeight(), 0.1f, 100.0f);
// create the mesh (of N by N points)
float di = float(WIDTH) / N;
float dj = float(HEIGHT) / N;
mesh.assign(NUM);
for(int i = 0; i < N; ++i) {
for(int j = 0; j < N; ++j) {
mesh[DX(i,j)].set(i * di, j * dj, 0, i/float(N), 1.0 - j/float(N));
}
}
// create VBO & VAO
glGenVertexArraysAPPLE(1, &vao);
glBindVertexArrayAPPLE(vao);
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, mesh.getNumBytes(), mesh.getPtr(), GL_STATIC_DRAW); // pass data to vbo
glEnableVertexAttribArray(pos_attrib); // enable vertex attribs for the pos.
glEnableVertexAttribArray(tex_attrib); // enable vertex attribs for the texcoord.
glVertexAttribPointer(pos_attrib, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, pos)); // where to find the pos atribute
glVertexAttribPointer(tex_attrib, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, tex)); // where to find the pos atribute
// Texture
// ----------
ofImage img;
if(!img.loadImage("http://www.roxlu.com/assets/downloads/freakday.png")) {
printf("cannot load.\n");
}
glEnable(GL_TEXTURE_2D);
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
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);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, img.getWidth(), img.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img.getPixels());
}
//--------------------------------------------------------------
void testApp::draw(){
glEnable(GL_BLEND);
// translate to center.
view_matrix.setTranslation(-HALF_WIDTH, -HALF_HEIGHT, -10.0f);
// draw with our shader.
shader.begin();
// we assign our texture to the texture unit 2 (only showing that we're not using the default (0) unit
glEnable(GL_TEXTURE_2D);
glActiveTexture(GL_TEXTURE2);
shader.setUniform1i("texture", 2);
glBindTexture(GL_TEXTURE_2D, tex);
shader.setUniformMatrix4f("view_matrix", view_matrix);
shader.setUniformMatrix4f("projection_matrix", projection_matrix);
glBindVertexArrayAPPLE(vao);
glDrawArrays(GL_POINTS, 0, mesh.size());
shader.end();
}
void testApp::debugDraw() {
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, ofGetWidth()/ofGetHeight(), 0.1, 100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glColor3f(1.0f, 1.0f, 1.0f);
glTranslatef(-HALF_WIDTH,-HALF_HEIGHT,-10.0f);
glPointSize(1);
glBegin(GL_POINTS);
for(int i = 0; i < N; ++i) {
for(int j = 0; j < N; ++j) {
glVertex3fv(mesh[DX(i,j)].pos.getPtr());
}
}
glEnd();
}
//--------------------------------------------------------------
void testApp::update(){
}
//--------------------------------------------------------------
void testApp::keyPressed(int key){
}
//--------------------------------------------------------------
void testApp::keyReleased(int key){
}
//--------------------------------------------------------------
void testApp::mouseMoved(int x, int y){
}
//--------------------------------------------------------------
void testApp::mouseDragged(int x, int y, int button){
}
//--------------------------------------------------------------
void testApp::mousePressed(int x, int y, int button){
}
//--------------------------------------------------------------
void testApp::mouseReleased(int x, int y, int button){
}
//--------------------------------------------------------------
void testApp::windowResized(int w, int h){
}
//--------------------------------------------------------------
void testApp::gotMessage(ofMessage msg){
}
//--------------------------------------------------------------
void testApp::dragEvent(ofDragInfo dragInfo){
}
#pragma once
#include "ofMain.h"
#define N 100
#define WIDTH 3
#define HEIGHT 5
#define HALF_WIDTH (WIDTH*0.5)
#define HALF_HEIGHT (HEIGHT*0.5)
#define NUM (N*N)
#define DX(i,j) (((j)*(N)) + (i))
static const string VS = " \
attribute vec4 pos; \
attribute vec2 tex; \
uniform mat4 view_matrix; \
uniform mat4 projection_matrix; \
varying vec2 vtex; \
\
void main() { \
gl_Position = projection_matrix * view_matrix * pos;\
vtex = tex; \
} ";
static const string FS = " \
uniform sampler2D texture; \
varying vec2 vtex; \
void main() { \
gl_FragColor = texture2D(texture, vtex); \
} ";
struct Vertex {
ofVec3f pos;
ofVec2f tex;
Vertex() {
}
Vertex(const float& x, const float& y, const float& z, const float& u, const float& v)
:pos(x,y,z)
,tex(u,v)
{
}
void set(const float& x, const float& y, const float& z, const float& u, const float& v) {
pos.set(x,y,z);
tex.set(u,v);
}
};
struct SimpleMesh {
int add(const Vertex& v) {
vertices.push_back(v);
return vertices.size() - 1;
}
float* getPtr() {
return &vertices[0].pos.x;
}
size_t size() {
return vertices.size();
}
size_t getNumBytes() {
return vertices.size() * sizeof(Vertex);
}
void assign(size_t num) {
vertices.assign(num, Vertex());
}
Vertex& operator[](const unsigned int& dx) {
return vertices.at(dx);
}
vector<Vertex> vertices;
};
class testApp : public ofBaseApp{
public:
void setup();
void update();
void draw();
void debugDraw();
void keyPressed(int key);
void keyReleased(int key);
void mouseMoved(int x, int y);
void mouseDragged(int x, int y, int button);
void mousePressed(int x, int y, int button);
void mouseReleased(int x, int y, int button);
void windowResized(int w, int h);
void dragEvent(ofDragInfo dragInfo);
void gotMessage(ofMessage msg);
ofShader shader;
ofMatrix4x4 view_matrix;
ofMatrix4x4 projection_matrix;
SimpleMesh mesh;
GLuint vbo;
GLuint vao;
GLuint tex;
};
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roxlu commented May 24, 2012

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