Implement cubic bezier surfaceHEADmaster

2 files changed, 30 insertions, 9 deletions

diff --git a/data/simple.vert b/data/simple.vert
index 1850a67..6fdb13b 100644
--- a/data/simple.vert
+++ b/data/simple.vert
@@ -3,6 +3,7 @@
 
 uniform mat4 mvp;
 uniform mat3 mv_normal;
+uniform mat4x3 k_uniform[4];
 
 layout(location = 0) in vec2 uv;
 
@@ -14,15 +15,21 @@ out vec3 normal_cs;
 
 void main(void)
 {
-	/* Center the region at the origin.  Assume that it's 7 units by 7
-	 * units.
-	 */
-	vec2 bias_uv = uv - 0.5;
-	vec4 position = vec4(bias_uv.x * 7.,
-			     0.0,
-			     bias_uv.y * 7.,
-			     1.0);
-	gl_Position = mvp * position;
+	vec4 uhat = vec4((1 - uv.x) * (1 - uv.x) * (1 - uv.x),
+			 3. * uv.x * (1 - uv.x) * (1 - uv.x),
+			 3. * uv.x * uv.x * (1 - uv.x),
+			 uv.x * uv.x * uv.x);
+	vec4 vhat = vec4((1 - uv.y) * (1 - uv.y) * (1 - uv.y),
+			 3. * uv.y * (1 - uv.y) * (1 - uv.y),
+			 3. * uv.y * uv.y * (1 - uv.y),
+			 uv.y * uv.y * uv.y);
+	mat4x3 m;
+	m[0] = k_uniform[0] * uhat;
+	m[1] = k_uniform[1] * uhat;
+	m[2] = k_uniform[2] * uhat;
+	m[3] = k_uniform[3] * uhat;
+
+	gl_Position = mvp * vec4(m * vhat, 1.0);
 
 	/* Transform the normal by the inverse-transpose of the model-view
 	 * matrix.
diff --git a/src/main.cpp b/src/main.cpp
index 34d4959..126daef 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -68,12 +68,15 @@ public:
 			glGetUniformLocation(this->program, "mvp");
 		this->mv_normal_uniform =
 			glGetUniformLocation(this->program, "mv_normal");
+		this->k_uniform =
+			glGetUniformLocation(this->program, "k_uniform");
 		this->light_dir_cs_uniform =
 			glGetUniformLocation(this->program, "light_dir_cs");
 	}
 
 	GLint mvp_uniform;
 	GLint mv_normal_uniform;
+	GLint k_uniform;
 	GLint light_dir_cs_uniform;
 };
 
@@ -373,6 +376,17 @@ Redisplay(void)
 	glUniformMatrix3fv(patch_program->mv_normal_uniform, 1, false,
 			   mv_normal);
 
+	float k_uniform[4][4][3];
+	for (int i = 0; i < 4; i++) {
+		for (int j = 0; j < 4; j++) {
+			for (int k = 0; k < 3; k++) {
+				k_uniform[i][j][k] = control_points[4 * i + j].values[k];
+			}
+		}
+	}
+	glUniformMatrix4x3fv(patch_program->k_uniform, 4, false,
+			     (const float *)k_uniform);
+
 	glDrawElements(mesh_sink->mode,
 		       mesh_sink->elt_count,
 		       GL_UNSIGNED_SHORT,