Agent D

12-03-2014, 04:19 PM

1. The point light seems to follow the camera? ... I tried to transform the Position by my projection matrix but that didnt seem to help.

Did you copy some of the code from tutorials? Typically lighting computations are done in camera relative space.

out mat4 proj_matrix;

uniform mat4 transform;

uniform mat4 projection;

Why does the fragment shader need an interpolated projection matrix? If you want to use the projection matrix in the fragment shader, you can use the uniform.

I don't see a reason to use it and you aren't going to have a different projection matrix for each vertex that you need to interpolate?

void main()

{

vertex_color = vec4(color, 1.0);

vertex_position = (projection * vec4(position, 1.0)).xyz;

vertex_normal = normalize(normal);

vertex_texture = uvcoords;

proj_matrix = projection;

gl_Position = (projection * vec4(position, 1.0));

}

You are assigning the projection matrix to the out qualifier as already explained above. Where do you use the "transform" matrix you specified as uniform above?

Are your input vertex positions already camera relative? Does the "projection" matrix contain the product of modelview and projection matrix?

vec4 calcDirectLight(float intensity, vec3 color, vec3 direction, vec3 normal)

{

.....

if(diffuseFactor > 0)

{

diffuseColor = vec4(color, 1.0) * intensity * diffuseFactor;

}

....

}

For some reason, I keep seeing things like this a lot lately. If diffuseFactor is zero (the case where you skip the computation), the result is zero

anyway, as it gets multiplied with diffuseFactor. This branch is a pointless, you are not getting any performance gains out of here, especially if

the compiler keeps the branch. Branching on the GPU is expensive.

void main()

{

vec4 totalLight = vec4(ambientLight, 1.0);

vec3 normal = normalize(vertex_normal);

vec3 newPos = (proj_matrix * vec4(pointLight.Position, 1.0)).xyz;

totalLight += calcDirectLight(directLight.Intensity, directLight.Color, directLight.Direction, normal);

totalLight += calcPointLight(pointLight.Intensity, pointLight.Color, newPos, pointLight.Atten.Constant, pointLight.Atten.Linear, pointLight.Atten.Exponent, normal);

vec4 texture_color = texture2D(sampler, vertex_texture.st);

if( texture_color == 0)

frag_color = vertex_color * totalLight;

else

frag_color = texture_color * vertex_color * totalLight;

}

So. You transform the light position with the projection matrix that you interpolate across the triangle for some reason instead of using the uniform.

If your "projection" matrix contains a camera transform and a projection matrix, you transform the light into clip space and use clip space fragment

positions for your light computation.

Could you try seperating camera and projective transformations and doing the lighting computations in view space instead of clip space? Instead of

interpolating camera and perspective transformations accross the triangles, you might want to use the uniform values, or perhaps move the transformation

into the vertexshader alltogehter and interpolating the resulting vector?

ParagonArcade

12-04-2014, 12:45 AM

I have another problem with my point light. It looked like it was working with a single plane, but with a cube its not working. The back and front faces aren't being lit. See picture.

1529

Lightning Calculations

vec3 calcDirectLight(float intensity, vec3 color, vec3 direction, vec3 normal)

{

float diffuseFactor = max(dot(normal, -direction), 0);

return color * intensity * diffuseFactor;

}

vec3 calcPointLight(float intensity, vec3 color, vec3 position, float constant, float linear, float exponent, vec3 normal)

{;

vec3 lightDir = vertex_position - position;

float lightDist = length(lightDir);

lightDir = lightDir / lightDist;

float attenuation = 1.0f / (0.1f + constant + linear * lightDist + exponent * lightDist * lightDist);

vec3 diffuse = calcDirectLight(intensity, color, lightDir, normal);

return diffuse * attenuation;

}

Cube Implementation

float halfWidth = 50.0f;

float halfLength = 50.0f;

float height = 100.0f;

float x_lo = -halfWidth;

float x_hi = halfWidth;

float z_lo = -halfLength;

float z_hi = halfLength;

float y_lo = 0;

float y_hi = height;

Vector3f pColor = Vector3f(1, 1, 1);

//Bottom Plane

Plane plane1 = Plane(

Vertex(Vector3f(x_lo, y_lo, z_lo), pColor, Vector3f(0, 1, 0), Vector2f(0, 0)),

Vertex(Vector3f(x_lo, y_lo, z_hi), pColor, Vector3f(0, 1, 0), Vector2f(1, 0)),

Vertex(Vector3f(x_hi, y_lo, z_hi), pColor, Vector3f(0, 1, 0), Vector2f(1, 1)),

Vertex(Vector3f(x_hi, y_lo, z_lo), pColor, Vector3f(0, 1, 0), Vector2f(0, 1)),

false,

false

);

//Top Plane

Plane plane2 = Plane(

Vertex(Vector3f(x_lo, y_hi, z_lo), pColor, Vector3f(0, -1, 0), Vector2f(0, 0)),

Vertex(Vector3f(x_lo, y_hi, z_hi), pColor, Vector3f(0, -1, 0), Vector2f(1, 0)),

Vertex(Vector3f(x_hi, y_hi, z_hi), pColor, Vector3f(0, -1, 0), Vector2f(1, 1)),

Vertex(Vector3f(x_hi, y_hi, z_lo), pColor, Vector3f(0, -1, 0), Vector2f(0, 1)),

false,

true

);

//Left Plane

Plane plane3 = Plane(

Vertex(Vector3f(x_lo, y_hi, z_hi), pColor, Vector3f(1, 0, 0), Vector2f(0, 0)),

Vertex(Vector3f(x_lo, y_lo, z_hi), pColor, Vector3f(1, 0, 0), Vector2f(1, 0)),

Vertex(Vector3f(x_lo, y_lo, z_lo), pColor, Vector3f(1, 0, 0), Vector2f(1, 1)),

Vertex(Vector3f(x_lo, y_hi, z_lo), pColor, Vector3f(1, 0, 0), Vector2f(0, 1)),

false,

false

);

//Right Plane

Plane plane4 = Plane(

Vertex(Vector3f(x_hi, y_hi, z_hi), pColor, Vector3f(-1, 0, 0), Vector2f(0, 0)),

Vertex(Vector3f(x_hi, y_lo, z_hi), pColor, Vector3f(-1, 0, 0), Vector2f(1, 0)),

Vertex(Vector3f(x_hi, y_lo, z_lo), pColor, Vector3f(-1, 0, 0), Vector2f(1, 1)),

Vertex(Vector3f(x_hi, y_hi, z_lo), pColor, Vector3f(-1, 0, 0), Vector2f(0, 1)),

false,

true

);

//Back Plane

Plane plane5 = Plane(

Vertex(Vector3f(x_hi, y_hi, z_lo), pColor, Vector3f(0, 0, 1), Vector2f(0, 0)),

Vertex(Vector3f(x_lo, y_hi, z_lo), pColor, Vector3f(0, 0, 1), Vector2f(1, 0)),

Vertex(Vector3f(x_lo, y_lo, z_lo), pColor, Vector3f(0, 0, 1), Vector2f(1, 1)),

Vertex(Vector3f(x_hi, y_lo, z_lo), pColor, Vector3f(0, 0, 1), Vector2f(0, 1)),

false,

false

);

//Front Plane

Plane plane6 = Plane(

Vertex(Vector3f(x_hi, y_hi, z_hi), pColor, Vector3f(0, 0, -1), Vector2f(0, 0)),

Vertex(Vector3f(x_lo, y_hi, z_hi), pColor, Vector3f(0, 0, -1), Vector2f(1, 0)),

Vertex(Vector3f(x_lo, y_lo, z_hi), pColor, Vector3f(0, 0, -1), Vector2f(1, 1)),

Vertex(Vector3f(x_hi, y_lo, z_hi), pColor, Vector3f(0, 0, -1), Vector2f(0, 1)),

false,

true

);

plane1.Draw();

plane2.Draw();

plane3.Draw();

plane4.Draw();

plane5.Draw();

plane6.Draw();

If I change the normal vector of the front/back faces, to some like (1,0,0) or (0,1,0) it lights the plane. So the lightning is working. Just something going on with normals along Z....??

ParagonArcade

12-04-2014, 06:39 PM

Still trying debug this. It looks like my Z-values are broken for normals. Below is a picture of the cube colored by the normal values.

frag_color = texture_color * abs(vec4(normal, 1.0));

The back plane should be a blue textured plane.... buts it black. Somehow the z-values are lost.

1530

Here is how I am setting up the constructors:

//Back Plane

Plane plane5 = Plane(

Vertex(Vector3f(x_hi, y_hi, z_lo), pColor, Vector3f(0, 0, -1), Vector2f(0, 0)),

Vertex(Vector3f(x_lo, y_hi, z_lo), pColor, Vector3f(0, 0, -1), Vector2f(1, 0)),

Vertex(Vector3f(x_lo, y_lo, z_lo), pColor, Vector3f(0, 0, -1), Vector2f(1, 1)),

Vertex(Vector3f(x_hi, y_lo, z_lo), pColor, Vector3f(0, 0, -1), Vector2f(0, 1)),

false,

false

);

...

void Plane::addVertices(vec_vertex vertices)

{

if (vbo)

{

//Bind

glBindBuffer(GL_ARRAY_BUFFER, vbo);

//Load Vertices

glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex)* vertices.size(), &vertices[0], GL_STATIC_DRAW);

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)0);

glEnableVertexAttribArray(0);

glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)sizeof(Vector3f));

glEnableVertexAttribArray(1);

glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)(sizeof(Vector3f)+sizeof(Vector3f)));

glEnableVertexAttribArray(2);

glVertexAttribPointer(3, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)(sizeof(Vector3f)+sizeof(Vector3f)+sizeof (Vector3f)));

glEnableVertexAttribArray(3);

}

}

...

Vertex::Vertex(Vector3f position, Vector3f color, Vector3f normal, Vector2f uvcoords)

{

Position = Vector3f(position.getX(), position.getY(), position.getZ());

Color = Vector3f(color.getX(), color.getY(), color.getZ());

Normal = Vector3f(normal.getX(), normal.getY(), normal.getZ());

UVCoords = Vector2f(uvcoords.getX(), uvcoords.getY());

}

...

Vector3f::Vector3f(float fx, float fy, float fz)

{

setX(fx);

setY(fy);

setZ(fz);

}

...

float Vector3f::getX() { return x; }

float Vector3f::getY() { return y; }

float Vector3f::getZ() { return z; }

void Vector3f::setX(float f) { x = f; }

void Vector3f::setY(float f) { y = f; }

void Vector3f::setZ(float f) { z = f; }

...

Still have no idea whats going on. What else could it be? Help plz :D

GClements

12-04-2014, 09:09 PM

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)0);

glEnableVertexAttribArray(0);

glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)sizeof(Vector3f));

glEnableVertexAttribArray(1);

glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)(sizeof(Vector3f)+sizeof(Vector3f)));

glEnableVertexAttribArray(2);

glVertexAttribPointer(3, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)(sizeof(Vector3f)+sizeof(Vector3f)+sizeof (Vector3f)));

glEnableVertexAttribArray(3);

Are you sure that attribute 2 should only have 2 components, not 3?

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