我需要一个简单的聚光灯着色器的帮助。圆锥内的所有顶点都应涂成黄色,圆锥外的所有顶点都应涂成黑色。我只是无法让它工作。我认为它与从世界到眼睛坐标的转换有关。
顶点着色器:
uniform vec4 lightPositionOC; // in object coordinates
uniform vec3 spotDirectionOC; // in object coordinates
uniform float spotCutoff; // in degrees
void main(void)
{
vec3 lightPosition;
vec3 spotDirection;
vec3 lightDirection;
float angle;
gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;
// Transforms light position and direction into eye coordinates
lightPosition = (lightPositionOC * gl_ModelViewMatrix).xyz;
spotDirection = normalize(spotDirectionOC * gl_NormalMatrix);
// Calculates the light vector (vector from light position to vertex)
vec4 vertex = gl_ModelViewMatrix * gl_Vertex;
lightDirection = normalize(vertex.xyz - lightPosition.xyz);
// Calculates the angle between the spot light direction vector and the light vector
angle = dot( normalize(spotDirection),
-normalize(lightDirection));
angle = max(angle,0);
// Test whether vertex is located in the cone
if(angle > radians(spotCutoff))
gl_FrontColor = vec4(1,1,0,1); // lit (yellow)
else
gl_FrontColor = vec4(0,0,0,1); // unlit(black)
}
片段着色器:
void main(void)
{
gl_FragColor = gl_Color;
}
编辑:
蒂姆是对的。这
if(angle > radians(spotCutoff))
应该:
if(acos(angle) < radians(spotCutoff))
新问题:
灯光似乎没有停留在场景中的固定位置,而是随着我向前或向后移动时锥体变小或变大而相对于我的相机移动。