I really don't understand what I am doing wrong in the perspective matrix creation code:
public static Matrix4f perspective(float fov, float width, float height,
float Near, float Far) {
Matrix4f projection = new Matrix4f(0);
float a = width / height;
float h = 1.0f/(float) Math.tan(Math.toRadians(fov / 2));
float depth = Near - Far;
// x&y
projection.values[0][0] = h/a;
projection.values[1][1] = h;
projection.values[2][2] = ((Far + Near)/depth);
projection.values[2][3] = 2.0f *(Far * Near) / depth;
projection.values[3][2] = -1.0f;
return projection;
}
Then when I send it to the shader I multiply it before with the modelview matrix like this:
math.mul(camera.getMatrix(), mesh.transform.getMatrix());
this means
P*M
in other languages that let you override operators, since I don't have a View Matrix from the camera.
What happens is that the 3d model is flat and when I rotate it, it gets really distorted. I tried the whole day to figure out what is wrong, but I had no luck.
What am I doing wrong ? Is there something I forgot about ?
EDIT:
Maybe there is something wrong with my multiplication code:
Multiplication code:
public static Matrix4f mul(Matrix4f m1, Matrix4f m2) {
Matrix4f result = new Matrix4f();
for (int j = 0; j < 4; j++) {
for (int i = 0; i < 4; i++) {
float sum = 0;
for (int n = 0; n < 4; n++) {
sum += m1.values[n][i] * m2.values[j][n];
}
result.values[j][i] = sum;
}
}
return result;
}
I even tried to swap the multiplication order from P * M
to M * P
but it still don't solve the problem.
I tried to transpose the matrix after multiplication:
Transpose code:
public static Matrix4f transpose(Matrix4f data)
{
Matrix4f result = new Matrix4f();
for(int y = 0; y < 4; y++)
{
for(int x = 0; x < 4; x++)
{
result.values[x][y] = data.values[y][x];
}
}
return result;
}
But that makes even worse distorsions.
EDIT:
Here are the raw printed memory contents of the projection matrix:
matrix[0][0] = 1.071111
matrix[0][1] = 0.0
matrix[0][2] = 0.0
matrix[0][3] = 0.0
matrix[1][0] = 0.0
matrix[1][1] = 1.428148
matrix[1][2] = 0.0
matrix[1][3] = 0.0
matrix[2][0] = 0.0
matrix[2][1] = 0.0
matrix[2][2] = -1.00002
matrix[2][3] = -0.0200002
matrix[3][0] = 0.0
matrix[3][1] = 0.0
matrix[3][2] = -1.0
matrix[3][3] = 0.0
Here is the ModelView Matrix (transformation)(The model position = 0, 0, 5):
model[0][0] = 1.0
model[0][1] = 0.0
model[0][2] = 0.0
model[0][3] = 0.0
model[1][0] = 0.0
model[1][1] = 1.0
model[1][2] = 0.0
model[1][3] = 0.0
model[2][0] = 0.0
model[2][1] = 0.0
model[2][2] = 1.0
model[2][3] = 5.0
model[3][0] = 0.0
model[3][1] = 0.0
model[3][2] = 0.0
model[3][3] = 1.0
Here is M*P
:
matrix[0][0] = 1.071111
matrix[0][1] = 0.0
matrix[0][2] = 0.0
matrix[0][3] = 0.0
matrix[1][0] = 0.0
matrix[1][1] = 1.428148
matrix[1][2] = 0.0
matrix[1][3] = 0.0
matrix[2][0] = 0.0
matrix[2][1] = 0.0
matrix[2][2] = -1.00002
matrix[2][3] = -5.0201
matrix[3][0] = 0.0
matrix[3][1] = 0.0
matrix[3][2] = -1.0
matrix[3][3] = -5.0
Here is P*M
:
matrix[0][0] = 1.071111
matrix[0][1] = 0.0
matrix[0][2] = 0.0
matrix[0][3] = 0.0
matrix[1][0] = 0.0
matrix[1][1] = 1.428148
matrix[1][2] = 0.0
matrix[1][3] = 0.0
matrix[2][0] = 0.0
matrix[2][1] = 0.0
matrix[2][2] = -6.00002
matrix[2][3] = -0.0200002
matrix[3][0] = 0.0
matrix[3][1] = 0.0
matrix[3][2] = -1.0
matrix[3][3] = 0.0
The answer belong to @derhass :
"From the numbers given, it looks like M*P is the correct result. However, you store the matrices transposed to what GL (somewhat) defaults to. So either you use vec4 * mat4 in the shader, and it should work, or you have to transpose the result for the GL and can use the default mat4 * vec4 convetion"
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