OpenGL ES creating a 2D mesh

Apprentice

Posts: 12
Joined: 2009.04

Post: #1

May 20, 2009 — 02:37 AM

Using OpenGL ES, I am trying to create a mesh that takes up the entire screen. My intention is to apply a texture to it and then distort it. My screen is 480x320 in size.

Here is what I have done:

Code:

#define kWindowWidth 480

#define kWindowHeight 360

#define kHorisontalDivisions 30

#define kVerticalDivisions 10

GLfloat pictureMeshVertices[kHorisontalDivisions][kVerticalDivisions][3];

GLfloat pictureMeshVerticesUnified[kHorisontalDivisions*kVerticalDivisions*3];

Code:

- (void)populateMesh

{

    int x;

    int y;

    int completedTriangles;

    float height = kWindowHeight/kVerticalDivisions;

    float width = kWindowWidth/kHorisontalDivisions;

    NSLog(@"width: %f, height: %f", width, height);

    for (y=0; y < kVerticalDivisions; y++) {

        for (x=0, completedTriangles=0; x < kHorisontalDivisions-1; x++, completedTriangles+=2) {

            pictureMeshVertices[completedTriangles][y][0] = (float)(x * width) + 0.0f;

            pictureMeshVertices[completedTriangles][y][1] = (float)(y * height) + height;

            pictureMeshVertices[completedTriangles][y][2] = 0.0f;

            pictureMeshVertices[completedTriangles+1][y][0] = (float) (x * width) + 0.0f;

            pictureMeshVertices[completedTriangles+1][y][1] = (float) ((y * height) + 0.0f);

            pictureMeshVertices[completedTriangles+1][y][2] = (float) 0.0f;

            NSLog(@"filling Line %i, %i: %f, %f, %f",completedTriangles, y,  pictureMeshVertices[completedTriangles][y][0], pictureMeshVertices[completedTriangles][y][1], pictureMeshVertices[completedTriangles][y][2] );

            NSLog(@"filling Line %i, %i: %f, %f, %f", completedTriangles+1, y,pictureMeshVertices[completedTriangles+1][y][0], pictureMeshVertices[completedTriangles+1][y][1], pictureMeshVertices[completedTriangles+1][y][2] );

        }

    }

    int i;

    int j;

    int k;

    int count = 0;

    for (j=0; j<kVerticalDivisions; j++) {

        for (i=0; i<kHorisontalDivisions; i++) {

            for (k=0; k<3; k++) {

                pictureMeshVerticesUnified[count] = pictureMeshVertices[i][j][k];

                //NSLog(@"%f",pictureMeshVerticesUnified[count] );

                count++;

            }

        }

    }

    NSLog(@"count: %i", count);

}

And the draw function will be like this:

Code:

glEnableClientState(GL_VERTEX_ARRAY);

glVertexPointer(3, GL_FLOAT, 0, pictureMeshVerticesUnified);

glPushMatrix();

    glDrawArrays(GL_LINE_STRIP, 0, kHorisontalDivisions*kVerticalDivisions*3);

glPopMatrix();

glDisableClientState(GL_VERTEX_ARRAY);

glDisableClientState(GL_COLOR_ARRAY);

However, I am getting this as a result.

It is clear that although the logic is somehow correct, I am forgetting something... Can anyone please point me in the right direction?

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