Hello,
I am newbie. I tried to create a mesh in openGL ES. But somewhere I am making some mistake. Can anyone show me the correct way to do this??? I just want to create a 2D mesh.
Also I want to map mesh with an image. Since I am developing under Iphone environment, I am not able to use GLU utility. Please help asap…
Thanks in advance. My question may be childish but I need to sort this
This is my setup View:
-(void)setupView:(GLView*)view
{
const GLfloat zNear = 0.01, zFar = 1000.0, fieldOfView = 45.0;
GLfloat size;
glEnable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0);
CGRect rect = view.bounds;
glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size /
(rect.size.width / rect.size.height), zNear, zFar);
glViewport(0, 0, rect.size.width, rect.size.height);
glMatrixMode(GL_MODELVIEW);
// Turn necessary features on
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_SRC_COLOR);
glGenTextures(1, &texture[0]);
glBindTexture(GL_TEXTURE_2D, texture[0]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
NSString *path = [[NSBundle mainBundle] pathForResource:@“texture” ofType:@“png”];
NSData *texData = [[NSData alloc] initWithContentsOfFile:path];
UIImage *image = [[UIImage alloc] initWithData:texData];
if (image == nil)
NSLog(@"Do real error checking here");
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
void *imageData = malloc( height * width * 4 );
CGContextRef context = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
// Flip the Y-axis
CGContextTranslateCTM (context, 0, height);
CGContextScaleCTM (context, 1.0, -1.0);
CGColorSpaceRelease( colorSpace );
CGContextClearRect( context, CGRectMake( 0, 0, width, height ) );
CGContextDrawImage( context, CGRectMake( 0, 0, width, height ), image.CGImage );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData);
CGContextRelease(context);
free(imageData);
[image release];
[texData release];
// Turn the first light on
glEnable(GL_LIGHT0);
// Define the ambient component of the first light
static const Color3D light0Ambient[] = {{0.4, 0.4, 0.4, 1.0}};
glLightfv(GL_LIGHT0, GL_AMBIENT, (const GLfloat *)light0Ambient);
// Define the diffuse component of the first light
static const Color3D light0Diffuse[] = {{0.8, 0.8, 0.8, 1.0}};
glLightfv(GL_LIGHT0, GL_DIFFUSE, (const GLfloat *)light0Diffuse);
// Define the position of the first light
// const GLfloat light0Position[] = {10.0, 10.0, 10.0};
static const Vertex3D light0Position[] = {{10.0, 10.0, 10.0}};
glLightfv(GL_LIGHT0, GL_POSITION, (const GLfloat *)light0Position);
[self populateMesh];
}
populateMesh function goes as follows:
-(void)populateMesh{
verticalDivisions = kVerticalDivisions;
horizontalDivisions = kHorisontalDivisions;
unsigned int verticesArrsize = (kVerticalDivisions * ((2 + kHorisontalDivisions * 2) * 3));
unsigned int textureCoordsArraySize = kVerticalDivisions * ((2 + kHorisontalDivisions * 2) * 2);
verticesArr = (GLfloat *)malloc(verticesArrsize * sizeof(GLfloat));
textureCoordsArr = (GLfloat*)malloc(textureCoordsArraySize * sizeof(GLfloat));
if (verticesArr == NULL) {
NSLog(@"verticesArr = NULL!");
}
float height = kWindowHeight/verticalDivisions;
float width = kWindowWidth/horizontalDivisions;
int i,j;
count = 0;
for (j=0; j<verticalDivisions; j++) {
for (i=0; i<=horizontalDivisions; i++, count+=6) { //2 vertices each time...
float currX = i * width;
float currY = j * height;
verticesArr[count] = currX;
verticesArr[count+1] = currY + height;
verticesArr[count+2] = 0.0f;
verticesArr[count+3] = currX;
verticesArr[count+4] = currY;
verticesArr[count+5] = 0.0f;
}
}
float xIncrease = 1.0f/horizontalDivisions;
float yIncrease = 1.0f/verticalDivisions;
int x,y;
count = 0;
for (y=0; y<verticalDivisions; y++) {
for (x=0; x<horizontalDivisions+1; x++, count+=4) {
float currX = x *xIncrease;
float currY = y * yIncrease;
textureCoordsArr[count] = (float)currX;
textureCoordsArr[count+1] = (float)currY + yIncrease;
textureCoordsArr[count+2] = (float)currX;
textureCoordsArr[count+3] = (float)currY;
}
}
}
and finally drawView as follows:
-
(void)drawView:(GLView*)view
{
static GLfloat rot = 0.0;glColor4f(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);glLoadIdentity();
glTranslatef(0.0, 0.0, -1.0);
glRotatef(rot, 1.0, 1.0, 1.0);glBindTexture(GL_TEXTURE_2D, texture[0]);
glVertexPointer(3, GL_FLOAT, 0, verticesArr);
glTexCoordPointer(3, GL_FLOAT, 0, textureCoordsArr);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glPushMatrix();{
int i;
for (i=0; i<verticalDivisions; i++) {
glDrawArrays(GL_TRIANGLE_STRIP, i*(horizontalDivisions2+2), horizontalDivisions2+2);
}
}glPopMatrix();
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
}
I cant upload resulting image…