Move light to world space and draw the shadows from PoV of the light.

2 files changed, 17 insertions, 9 deletions

diff --git a/src/phong.vert b/src/phong.vert
index c561488..fae74c1 100755
--- a/src/phong.vert
+++ b/src/phong.vert
@@ -2,8 +2,10 @@
 uniform mat4 mvp; // object -> world -> eye -> screen
 uniform mat4 mv;  // object -> world -> eye
 uniform mat4 m;   // object -> world
+uniform mat4 v;   // world -> eye
 
 uniform vec4 eye; // Eye position in world space
+uniform vec4 light_pos_es; // Light position in world-space.
 
 // These two are in object space
 attribute vec4 normal;
@@ -22,10 +24,6 @@ varying vec3 eye_ss;
 
 varying vec2 uv_coord = uv;
 
-/* Position of the light in eye-space.
- */
-const vec3 light_pos_es = vec3(0.0, 3.0, 0.0);
-
 void main(void)
 {
 	gl_Position = mvp * gl_Vertex;
@@ -36,7 +34,7 @@ void main(void)
 	mat3 tbn = mat3(tangent_es, bitangent_es, normal_es);
 
 	vec3 vertex_pos_es = vec3(mv * gl_Vertex);
-	vec3 light_direction_es = light_pos_es - vertex_pos_es;
+	vec3 light_direction_es = vec3(light_pos_es) - vertex_pos_es;
 
 	/* Surface space vectors for lighting */
 	light_ss = normalize(light_direction_es * tbn);
diff --git a/src/scene.cpp b/src/scene.cpp
index 9f72b13..333fbee 100755
--- a/src/scene.cpp
+++ b/src/scene.cpp
@@ -39,6 +39,7 @@ namespace Scene {
 static bool anim = true;
 
 static GLUvec4 eye(0.0, 1.5f, 10.0f, 0.0f);
+static GLUvec4 light(0.0, 6.0f, 0.0f, 0.0f);
 
 /**
  * Points in 3-space that the camera must hit.
@@ -104,6 +105,7 @@ static GLint phong_m_location;
 static GLint phong_s_location;
 static GLint phong_sampler_location;
 static GLint phong_eye_location;
+static GLint phong_light_location;
 
 static GLuint shadow_prog;
 static GLint shadow_mvp_location;
@@ -113,13 +115,13 @@ static GLuint cubemap;
 static patch_set_info *object = NULL;
 
 void
-Render()
+Render(const GLUvec4 &look_at)
 {
 	const patch_set_info *info = object;
 
 	const GLUvec4 ref(0.0f, 0.0f, 0.0f, 1.0f);
 	const GLUvec4 up(0.0f, 1.0f, 0.0f, 0.0f);
-	const GLUmat4 view(gluLookAt(eye, ref, up));
+	const GLUmat4 view(gluLookAt(look_at, ref, up));
 
 	GLUmat4 model(gluRotate(GLUvec4(1.0, 0.0, 0.0, 0.0), 3.0 * M_PI_2));
 
@@ -160,6 +162,9 @@ Render()
 			glUniformMatrix4fv(phong_m_location, 1, false, (float *) &m);
 			glUniform1i(phong_sampler_location, 0);
 			glUniform4fv(phong_eye_location, 1, eye.values);
+
+			GLUvec4 light_pos_es = view * light;
+			glUniform4fv(phong_light_location, 1, light_pos_es.values);
 		}
 
 		glMultiDrawElements(info->mode, info->count, info->type,
@@ -183,14 +188,14 @@ void
 RenderPhong()
 {
 	glUseProgram(phong_prog);
-	Render();
+	Render(eye);
 }
 
 void
 RenderShadow()
 {
 	glUseProgram(shadow_prog);
-	Render();
+	Render(light);
 }
 
 
@@ -204,6 +209,10 @@ lerp(GLUvec4 p0, GLUvec4 p1, float t)
 static void
 update_camera(float total_t)
 {
+	/* Move the light in a circle */
+	const float light_t = 0.628318530717959f /* 2pi/10 */ * total_t;
+	light = GLUvec4(10.0*cos(light_t), 8.0, 10.0*sin(light_t), 0.0);
+
 	/* Figure out which segment is active based on the
 	 * following rules:
 	 * Segment 0 is active from [0, 4)  seconds (4 seconds)
@@ -280,6 +289,7 @@ setup_shader()
 	phong_mv_location = glGetUniformLocation(phong_prog, "mv");
 	phong_m_location = glGetUniformLocation(phong_prog, "m");
 	phong_eye_location = glGetUniformLocation(phong_prog, "eye");
+	phong_light_location = glGetUniformLocation(phong_prog, "light_pos_es");
 	phong_s_location = glGetUniformLocation(phong_prog, "s");
 	phong_sampler_location = glGetUniformLocation(phong_prog, "sampler");