Apply the shadow map to the ground plane.

6 files changed, 46 insertions, 4 deletions

diff --git a/glass.c b/glass.c
index 091b32f..36bb3fe 100644
--- a/glass.c
+++ b/glass.c
@@ -77,6 +77,8 @@ struct uniform_desc ground_uniforms[GROUND_UNIFORM_MAX] = {
 	[GROUND_UNIFORM_MV] = { "mv" },
 	[GROUND_UNIFORM_MVP] = { "mvp" },
 	[GROUND_UNIFORM_LIGHT_EYE] = { "light_eye" },
+	[GROUND_UNIFORM_LIGHT_MVP] = { "light_mvp" },
+	[GROUND_UNIFORM_SHADOW_SAMPLER] = { "shadow_sampler" },
 };
 
 struct uniform_desc shadow_uniforms[SHADOW_UNIFORM_MAX] = {
@@ -810,6 +812,7 @@ load_ground_program(void)
 
 	ground_prog = load_program("ground", ground_uniforms,
 				   ARRAY_SIZE(ground_uniforms));
+	glUniform1i(ground_uniforms[GROUND_UNIFORM_SHADOW_SAMPLER].location, 0);
 }
 
 static void
diff --git a/glass.h b/glass.h
index 93628f9..4db5395 100644
--- a/glass.h
+++ b/glass.h
@@ -40,6 +40,8 @@ enum ground_uniform_list {
 	GROUND_UNIFORM_MV,
 	GROUND_UNIFORM_MVP,
 	GROUND_UNIFORM_LIGHT_EYE,
+	GROUND_UNIFORM_LIGHT_MVP,
+	GROUND_UNIFORM_SHADOW_SAMPLER,
 	GROUND_UNIFORM_MAX
 };
 
@@ -66,6 +68,7 @@ extern struct revolved_object ring;
 extern GLUvec4 ring_bounding_sphere_center_world;
 extern float ring_bounding_sphere_radius;
 extern GLuint shadow_tex;
+extern GLUmat4 world_to_light_ndc;
 
 void do_ring_drawelements(void);
 
diff --git a/ground.c b/ground.c
index 69e7453..59f4dd9 100644
--- a/ground.c
+++ b/ground.c
@@ -53,13 +53,30 @@ static void
 install_ground_transform(void)
 {
 	GLUmat4 mvp;
+	GLUmat4 world_to_shadow_texcoords;
+	GLUmat4 temp;
 
 	gluMult4m_4m(&mvp, &projection, &world_to_eye);
 
+	/* Setup the viewport translation to map light NDC to texcoords.
+	 */
+	memcpy(&temp, &gluIdentityMatrix, sizeof(gluIdentityMatrix));
+	temp.col[0].values[0] = (1.0 - 0.0) / 2.0;
+	temp.col[0].values[3] = temp.col[0].values[0] + 0.0;
+	temp.col[1].values[1] = (1.0 - 0.0) / 2.0;
+	temp.col[1].values[3] = temp.col[1].values[1] + 0.0;
+	temp.col[2].values[2] = (1.0 - 0.0) / 2.0;
+	temp.col[2].values[3] = (1.0 - 0.0) / 2.0;
+
+	gluMult4m_4m(&world_to_shadow_texcoords, &temp, &world_to_light_ndc);
+
+	/* Note that ground object coordinates are already in world space. */
 	glUniformMatrix4fv(ground_uniforms[GROUND_UNIFORM_MV].location, 1, 0,
 			   (float *)&world_to_eye);
 	glUniformMatrix4fv(ground_uniforms[GROUND_UNIFORM_MVP].location, 1, 0,
 			   (float *)&mvp);
+	glUniformMatrix4fv(ground_uniforms[GROUND_UNIFORM_LIGHT_MVP].location, 1, 0,
+			   (float *)&world_to_shadow_texcoords);
 }
 
 void
@@ -75,6 +92,10 @@ draw_ground(void)
 	glUseProgram(ground_prog);
 	install_ground_transform();
 
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, shadow_tex);
+	glEnable(GL_TEXTURE_2D);
+
 	glBindVertexArray(ground_obj);
 
 	for (v = 0; v < ground_size - 1; v++) {
@@ -99,6 +120,7 @@ draw_ground(void)
 				       indices[v]);
 		}
 	}
+	glDisable(GL_TEXTURE_2D);
 }
 
 void
diff --git a/ground.frag b/ground.frag
index a9cd20c..dca71f2 100644
--- a/ground.frag
+++ b/ground.frag
@@ -1,10 +1,12 @@
 uniform vec3 light_eye;
+varying vec2 shadow_coords;
 varying vec3 vertex_eye;
+uniform sampler2D shadow_sampler;
 
 void main()
 {
 	vec3 normal = vec3(0.0, 0.0, 1.0);
-	const vec4 material_color = vec4(1.0, 0.7, 0.3, 0.0);
+	vec4 material_color = texture2D(shadow_sampler, shadow_coords);
 	vec3 l = normalize(light_eye - vertex_eye);
 	vec3 v = normalize(-vertex_eye);
 	vec3 h = normalize(l + v);
diff --git a/ground.vert b/ground.vert
index 549636b..f4d7713 100644
--- a/ground.vert
+++ b/ground.vert
@@ -5,7 +5,8 @@ varying vec3 eye_surf;
 varying vec3 tangent_surf;
 */
 varying vec3 vertex_eye;
-uniform mat4 mvp, mv;
+varying vec2 shadow_coords;
+uniform mat4 mvp, mv, light_mvp;
 
 void main()
 {
@@ -14,6 +15,7 @@ void main()
 */
 	gl_Position = mvp * gl_Vertex;
 	vertex_eye = vec3(mv * gl_Vertex);
+	shadow_coords = (light_mvp * gl_Vertex).xy;
 /*
 	mat3 tbn = mat3(t,
 			cross(n, t),
diff --git a/shadow_map.c b/shadow_map.c
index 290343a..59e7650 100644
--- a/shadow_map.c
+++ b/shadow_map.c
@@ -40,7 +40,8 @@
 
 extern int no_multi_draw_arrays;
 extern GLUvec4 eye_world;
-static GLUmat4 world_to_light_eye, world_to_light_ndc;
+static GLUmat4 world_to_light_eye;
+GLUmat4 world_to_light_ndc;
 GLuint shadow_tex = 0, shadow_fbo;
 
 static void
@@ -55,6 +56,11 @@ calculate_light_projection(void)
 	light_up.values[2] = 0.0;
 	light_up.values[3] = 1.0;
 
+	/*
+	print_GLUvec4("light_world", &light_world);
+	print_GLUvec4("ring_center", &ring_bounding_sphere_center_world);
+	print_GLUvec4("light_up   ", &light_up);
+	*/
 	/* Transform for looking from they eye's point of view at the pile of
 	 * rings.
 	 */
@@ -62,7 +68,7 @@ calculate_light_projection(void)
 		    &light_world,
 		    &ring_bounding_sphere_center_world,
 		    &light_up);
-	gluPerspective4(&temp, 90, /*XXX: calculate me */
+	gluPerspective4(&temp, 120, /*XXX: calculate me */
 			       1.0, /* we're using a bounding sphere, w == h */
 			       0.2, 40);
 	gluMult4m_4m(&world_to_light_ndc, &temp, &world_to_light_eye);
@@ -104,6 +110,10 @@ generate_rings_shadowmap(void)
 				GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 		glTexParameteri(GL_TEXTURE_2D,
 				GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+		glTexParameteri(GL_TEXTURE_2D,
+				GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+		glTexParameteri(GL_TEXTURE_2D,
+				GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8,
 			     shadow_width, shadow_height, 0,
 			     GL_RGBA, GL_FLOAT, NULL);