update: played with lighting

shaders/terrain-vert.glsl

@@ -3,6 +3,7 @@
 #define highp
 #line 0
 attribute highp vec4 attr_pos;
+attribute lowp vec3 attr_normal;
 attribute lowp vec3 attr_color;
 
 uniform highp mat4 uni_mvp;
@@ -10,6 +11,11 @@ uniform highp mat4 uni_mvp;
 varying lowp vec3 vary_color;
 
 void main (void) {
-	vary_color = attr_color;
+	vec3 sun_dir = normalize (vec3 (1.0, 1.0, 4.0));
+	
+	vec3 sun_light = vec3 (1.0, 0.75, 0.5) * max (0.0, dot (attr_normal, sun_dir));
+	vec3 sky_light = vec3 (0.0, 0.25, 0.5) * (attr_normal.z * 0.5 + 0.5);
+	
+	vary_color = sqrt (attr_color * (sun_light + sky_light));
 	gl_Position = uni_mvp * attr_pos;
 }

src/bin/terrain.rs

@@ -45,6 +45,7 @@ struct GraphicsContext {
 
 struct ShaderLocations {
 	attr_pos: u32,
+	attr_normal: u32,
 	attr_color: u32,
 	uni_mvp: i32,
 }
@@ -57,6 +58,7 @@ impl ShaderLocations {
 		
 		Ok (Self {
 			attr_pos:    attr ("attr_pos")?,
+			attr_normal: attr ("attr_normal")?,
 			attr_color:  attr ("attr_color")?,
 			uni_mvp:     uni ("uni_mvp")?,
 		})
@@ -68,6 +70,7 @@ fn draw_graphics (ctx: &GraphicsContext, state: &GameState)
 {
 	let shader_locs = &ctx.shader_locations;
 	let attr_pos = shader_locs.attr_pos;
+	let attr_normal = shader_locs.attr_normal;
 	let attr_color = shader_locs.attr_color;
 	let uni_mvp = shader_locs.uni_mvp;
 	
@@ -97,15 +100,17 @@ fn draw_graphics (ctx: &GraphicsContext, state: &GameState)
 	ctx.shader_program.use_program ();
 	glezz::enable_vertex_attrib_array (Some (attr_pos));
 	glezz::enable_vertex_attrib_array (Some (attr_color));
+	glezz::enable_vertex_attrib_array (Some (attr_normal));
 	
 	ctx.vertex_buffer.bind ();
 	ctx.index_buffer.bind ();
 	
 	unsafe {
 		let num_quads = 64 * 64;
-		let stride = 4 * 6;
+		let stride = 4 * 9;
 		gl::VertexAttribPointer (attr_pos, 3, gl::FLOAT, 0, stride, 0 as *const u8 as *const c_void);
-		gl::VertexAttribPointer (attr_color, 3, gl::FLOAT, 0, stride, (4 * 3) as *const u8 as *const c_void);
+		gl::VertexAttribPointer (attr_normal, 3, gl::FLOAT, 0, stride, (4 * 3) as *const u8 as *const c_void);
+		gl::VertexAttribPointer (attr_color, 3, gl::FLOAT, 0, stride, (4 * 6) as *const u8 as *const c_void);
 		
 		gl::DrawRangeElements (gl::TRIANGLES, 0, num_quads * 4, num_quads as i32 * 6, gl::UNSIGNED_INT, 0 as *const u8 as *const c_void);
 	}
@@ -154,22 +159,28 @@ fn main () -> anyhow::Result <()> {
 	let mut indexes = vec![];
 	let mut start_index = 0;
 	
-	let height_fn = |x, y| {
-		let x = x - 32.0;
-		let y = y - 32.0;
+	let bump_at = |bump_x, bump_y, x, y| {
+		let x = x - bump_x;
+		let y = y - bump_y;
 		
 		let d = x * x + y * y;
 		
 		f32::max (0.0, 5.0 - d * 0.125)
 	};
 	
+	let height_fn = |(x, y)| {
+		bump_at (32.0, 32.0, x, y) +
+		bump_at (64.0, 32.0, x, y) +
+		bump_at (32.0, 48.0, x, y)
+	};
+	
 	for y in 0..64 {
 		for x in 0..64 {
 			let (r, g, b) = if (x + y) % 2 == 0 {
 				(0.4, 0.4, 0.4)
 			}
 			else {
-				(0.6, 0.6, 0.6)
+				(0.5, 0.5, 0.5)
 			};
 			
 			let x = x as f32;
@@ -183,9 +194,27 @@ fn main () -> anyhow::Result <()> {
 				(x + 0.0, y + 1.0),
 			];
 			
-			for (x, y) in &xys {
+			let zs = [
+				height_fn (xys [0]),
+				height_fn (xys [1]),
+				height_fn (xys [2]),
+				height_fn (xys [3]),
+			];
+			
+			let slope_x = (zs [1] + zs [2]) - (zs [0] + zs [3]);
+			let slope_y = (zs [2] + zs [3]) - (zs [0] + zs [1]);
+			
+			let tangent_x = Vec3::from ((1.0, 0.0, slope_x));
+			let tangent_y = Vec3::from ((0.0, 1.0, slope_y));
+			let normal = Vec3::cross (tangent_x, tangent_y)
+			.normalize ();
+			
+			let (nx, ny, nz) = normal.into ();
+			
+			for ((x, y), z) in xys.iter ().zip (&zs) {
 				vertexes.extend (&[
-					*x, *y, height_fn (*x, *y),
+					*x, *y, *z,
+					nx, ny, nz,
 					r, g, b,
 				])
 			}