I stuck with implementing Gouraud smooth shading. I'm missing something and I need help.
First about diffuse lighting. To get diffuse light I'm using this formula:
Id * Kd * max( dot(N,L), 0.0)
I should get my diffuse color and I will add it to my ambient color.
Next shading. Gouraud shading is a shading per vertex. I found Gouraud shading algorithm in this lectures
As I understood this algorithm:
- Determine the normal at each polygon vertex
vec3 N = mat3(normalMatrix) * normals;
- Apply an illumination model to each vertex to calculate the vertex intensity
float labertian = max(dot(N, L), 0.0);
vec4 color = vec4(intensityAmbientColor * ambientColor
+ intensityDiffuseColor * diffuseColor * labertian, 1.0);
- Linearly interpolate the vertex intensities over the surface polygon
v_color = color;
This is the output image
What do I missing here? vertex shader:
attribute vec3 coordinates;
attribute vec3 normals;
/** MVP */
uniform mat4 modelMatrix;
uniform mat4 projectionMatrix;
uniform mat4 viewMatrix;
uniform mat4 normalMatrix;
// uniform mat4 viewModelMatrixl
/** LIGHT */
uniform vec3 ambientColor;
uniform float intensityAmbientColor;
uniform vec3 diffuseColor;
uniform float intensityDiffuseColor;
uniform vec3 cameraCoordinates;
uniform vec3 lightCoordinates;
varying vec4 v_color;
void main() {
gl_Position = projectionMatrix *
viewMatrix *
modelMatrix *
vec4(coordinates, 1.0);
vec3 surfaceWorldPosition = (
viewMatrix
* modelMatrix
* vec4(coordinates, 1.0)
).xyz;
vec3 L = lightCoordinates - surfaceWorldPosition;
vec3 V = cameraCoordinates - surfaceWorldPosition;
vec3 N = mat3(normalMatrix) * normals;
float labertian = max(dot(N, L), 0.0);
v_color = vec4(intensityAmbientColor * ambientColor
+ intensityDiffuseColor * diffuseColor * labertian, 1.0);
}
fragment shader:
precision mediump float;
varying vec4 v_color;
void main() {
gl_FragColor = v_color;
}
