OpenGL Projection matrix won't allow displaying anything
- by user272973
I'm trying to get some basic OpenGL-ES with Shaders to run on the iPhone, based on some examples.
For some reason my projection matrix refuses to result in something on the screen. It feels like a clipping plane is set very near but that contradicts with the values I supply. If I render the same scene with an Orthogonal projection matrix I see my object just no perspective obviously.
Here's the code that generates the projection matrix:
esPerspective(&proj, 45.f, 768.0/1024.0, 1.f, 10000.f);
void esPerspective(ESMatrix *result, float fovy, float aspect, float nearZ, float farZ)
{
float frustumW, frustumH;
frustumH = tanf( fovy / 360.0f * PI ) * nearZ;
frustumW = frustumH * aspect;
esFrustum( result, -frustumW, frustumW, -frustumH, frustumH, nearZ, farZ );
}
void esFrustum(ESMatrix *result, float left, float right, float bottom, float top, float nearZ, float farZ)
{
float deltaX = right - left;
float deltaY = top - bottom;
float deltaZ = farZ - nearZ;
ESMatrix frust;
if ( (nearZ <= 0.0f) || (farZ <= 0.0f) ||
(deltaX <= 0.0f) || (deltaY <= 0.0f) || (deltaZ <= 0.0f) )
return;
frust.m[0][0] = 2.0f * nearZ / deltaX;
frust.m[0][1] = frust.m[0][2] = frust.m[0][3] = 0.0f;
frust.m[1][1] = 2.0f * nearZ / deltaY;
frust.m[1][0] = frust.m[1][2] = frust.m[1][3] = 0.0f;
frust.m[2][0] = (right + left) / deltaX;
frust.m[2][1] = (top + bottom) / deltaY;
frust.m[2][2] = -(nearZ + farZ) / deltaZ;
frust.m[2][3] = -1.0f;
frust.m[3][2] = -2.0f * nearZ * farZ / deltaZ;
frust.m[3][0] = frust.m[3][1] = frust.m[3][3] = 0.0f;
esMatrixMultiply(result, &frust, result);
}
My projection matrix comes out as:
[3.21, 0, 0, 0]
[0, 2.41, 0, 0]
[0, 0, -1, -1]
[0, 0, -2, 0]
Even if I manually set the [3][3] cell to 1 I still don't see anything.
Any ideas?
