Wasabi

04-06-2011, 09:37 AM

I have the following GLSL vertex shader code:

#version 330

struct Matrix

{

vec4 row1;

vec4 row2;

vec4 row3;

vec4 row4;

};

uniform Matrix ModelviewProjection;

in vec3 in_Position;

in vec3 in_Color;

out vec3 ex_Color;

void main(void)

{

//gl_Position = vec4(in_Position.x, in_Position.y, in_Position.z, 1.0);

vec4 Position = vec4(in_Position.x, in_Position.y, in_Position.z, 1.0);

vec4 x,y,z,w;

x = ModelviewProjection.row1*Position;

y = ModelviewProjection.row2*Position;

z = ModelviewProjection.row3*Position;

gl_Position.x = x.x+x.y+x.z;

gl_Position.y = y.x+y.y+y.z;

gl_Position.z = z.x+z.y+z.z;

gl_Position.w = 1;

ex_Color = in_Color;

}

At first, the uniform is defined as an identity matrix, i.e. gl_Position=in_Position. If I "push" (using my own function) a rotation matrix onto the uniform, the image shown on screen is rotated. However, if I add any translation data, it is ignored.

That is, if I have the uniform at its default identity value and push the following matrix at the Modelview part:

[cos(30),-sin(30),0,1,

sin(30),cos(30),0,0,

0,0,1,0

0,0,0,1]

The end product of Projection*Modelview*Rotation=Rotation, since the others are identity matricies.

Now, if I update the uniform to its new value (=Rotation) and redraw the screen, the image appears rotated by 30 degrees, as it should, however, the x-translation is ignored. If instead the matrix is:

[1,0,0,1,

0,1,0,0,

0,0,1,0,

0,0,0,1]

The matrix might as well be an identity, since nothing happens.

Am I doing something wrong?

#version 330

struct Matrix

{

vec4 row1;

vec4 row2;

vec4 row3;

vec4 row4;

};

uniform Matrix ModelviewProjection;

in vec3 in_Position;

in vec3 in_Color;

out vec3 ex_Color;

void main(void)

{

//gl_Position = vec4(in_Position.x, in_Position.y, in_Position.z, 1.0);

vec4 Position = vec4(in_Position.x, in_Position.y, in_Position.z, 1.0);

vec4 x,y,z,w;

x = ModelviewProjection.row1*Position;

y = ModelviewProjection.row2*Position;

z = ModelviewProjection.row3*Position;

gl_Position.x = x.x+x.y+x.z;

gl_Position.y = y.x+y.y+y.z;

gl_Position.z = z.x+z.y+z.z;

gl_Position.w = 1;

ex_Color = in_Color;

}

At first, the uniform is defined as an identity matrix, i.e. gl_Position=in_Position. If I "push" (using my own function) a rotation matrix onto the uniform, the image shown on screen is rotated. However, if I add any translation data, it is ignored.

That is, if I have the uniform at its default identity value and push the following matrix at the Modelview part:

[cos(30),-sin(30),0,1,

sin(30),cos(30),0,0,

0,0,1,0

0,0,0,1]

The end product of Projection*Modelview*Rotation=Rotation, since the others are identity matricies.

Now, if I update the uniform to its new value (=Rotation) and redraw the screen, the image appears rotated by 30 degrees, as it should, however, the x-translation is ignored. If instead the matrix is:

[1,0,0,1,

0,1,0,0,

0,0,1,0,

0,0,0,1]

The matrix might as well be an identity, since nothing happens.

Am I doing something wrong?