Rework the fog, so it doesn't need the alpha component anymore.

This also fixes #93 as a side effect
This could also theoretically improve performance due to using a smaller image format, but I couldn't measure a bit difference on my computer, it might be that my driver/hardware just pads the alpha component.

assets/cubyz/shaders/bloom/color_extractor_downsample.fs

@@ -43,22 +43,20 @@ float calculateFogDistance(float depthBufferValue, float fogDensity) {
 	}
 }
 
+vec3 applyFrontfaceFog(float fogDistance, vec3 fogColor, vec3 inColor) {
+	float fogFactor = exp(fogDistance);
+	inColor *= fogFactor;
+	inColor += fogColor;
+	inColor -= fogColor*fogFactor;
+	return inColor;
+}
+
 vec3 fetch(ivec2 pos) {
 	vec4 rgba = texelFetch(color, pos, 0);
 	float densityAdjustment = sqrt(dot(tanXY*(normalizedTexCoords*2 - 1), tanXY*(normalizedTexCoords*2 - 1)) + 1);
 	float fogDistance = calculateFogDistance(texelFetch(depthTexture, pos, 0).r, fog.density*densityAdjustment);
 	vec3 fogColor = fog.color;
-	float fogFactor = exp(fogDistance);
-	vec4 sourceColor = vec4(fogColor, 1);
-	sourceColor.a = 1.0/fogFactor;
-	sourceColor.rgb *= sourceColor.a;
-	sourceColor.rgb -= fogColor;
-	vec3 source2Color = vec3(1);
-	rgba = vec4(
-		source2Color*rgba.rgb + rgba.a*sourceColor.rgb,
-		rgba.a*sourceColor.a
-	);
-	if(rgba.a < 1) return vec3(0); // Prevent t-junctions from transparency from making a huge mess.
+	rgba.rgb = applyFrontfaceFog(fogDistance, fog.color, rgba.rgb);
 	return rgba.rgb/rgba.a;
 }
 

assets/cubyz/shaders/chunks/transparent_fragment.fs

@@ -105,17 +105,19 @@ float calculateFogDistance(float depthBufferValue, float fogDensity) {
 
 void applyFrontfaceFog(float fogDistance, vec3 fogColor) {
 	float fogFactor = exp(fogDistance);
-	fragColor.a = 1.0/fogFactor;
-	fragColor.rgb = fragColor.a*fogColor;
-	fragColor.rgb -= fogColor;
+	fragColor.rgb *= fogFactor;
+	fragColor.rgb += fogColor;
+	fragColor.rgb -= fogColor*fogFactor;
+	fragColor.a = fogFactor;
 }
 
 void applyBackfaceFog(float fogDistance, vec3 fogColor) {
 	float fogFactor = exp(fogDistance);
 	float oldAlpha = fragColor.a;
-	fragColor.a *= fogFactor;
-	fragColor.rgb -= oldAlpha*fogColor;
-	fragColor.rgb += fragColor.a*fogColor;
+	fragColor.rgb *= 1.0/fogFactor;
+	fragColor.rgb -= fogColor/fogFactor;
+	fragColor.rgb += fogColor;
+	fragColor.a *= 1.0/fogFactor;
 }
 
 vec2 getTextureCoordsNormal(vec3 voxelPosition, int textureDir) {
@@ -181,7 +183,7 @@ void main() {
 
 		// Apply the texture+absorption
 		fragColor.rgb *= blendColor.rgb;
-		fragColor.rgb += textureColor.rgb*fragColor.a;
+		fragColor.rgb += textureColor.rgb;
 
 		// Apply the air fog:
 		applyBackfaceFog(airFogDistance, fog.color);
@@ -193,9 +195,11 @@ void main() {
 		vec4 textureColor = texture(texture_sampler, vec3(getTextureCoordsNormal(startPosition/16, faceNormal), textureIndex))*vec4(ambientLight*normalVariation, 1);
 		blendColor.rgb = vec3(1 - textureColor.a);
 		fragColor.rgb *= blendColor.rgb;
-		fragColor.rgb += textureColor.rgb*textureColor.a*fragColor.a;
+		fragColor.rgb += textureColor.rgb*textureColor.a;
 
 		// Apply the block fog:
 		applyBackfaceFog(fogDistance, fogColor);
 	}
+	blendColor.rgb *= fragColor.a;
+	fragColor.a = 1;
 }

assets/cubyz/shaders/deferred_render_pass.fs

@@ -41,22 +41,19 @@ float calculateFogDistance(float depthBufferValue, float fogDensity) {
 	}
 }
 
+vec3 applyFrontfaceFog(float fogDistance, vec3 fogColor, vec3 inColor) {
+	float fogFactor = exp(fogDistance);
+	inColor *= fogFactor;
+	inColor += fogColor;
+	inColor -= fogColor*fogFactor;
+	return inColor;
+}
+
 void main() {
 	fragColor = texture(color, texCoords);
 	float densityAdjustment = sqrt(dot(tanXY*(texCoords*2 - 1), tanXY*(texCoords*2 - 1)) + 1);
 	float fogDistance = calculateFogDistance(texelFetch(depthTexture, ivec2(gl_FragCoord.xy), 0).r, fog.density*densityAdjustment);
-	vec3 fogColor = fog.color;
-	float fogFactor = exp(fogDistance);
-	vec4 sourceColor = vec4(fogColor, 1);
-	sourceColor.a = 1.0/fogFactor;
-	sourceColor.rgb *= sourceColor.a;
-	sourceColor.rgb -= fogColor;
-	vec3 source2Color = vec3(1);
-	fragColor = vec4(
-		source2Color*fragColor.rgb + fragColor.a*sourceColor.rgb,
-		fragColor.a*sourceColor.a
-	);
-	fragColor.rgb /= fragColor.a;
+	fragColor.rgb = applyFrontfaceFog(fogDistance, fog.color, fragColor.rgb);
 	float maxColor = max(1.0, max(fragColor.r, max(fragColor.g, fragColor.b)));
 	fragColor.rgb = fragColor.rgb/maxColor;
 }

assets/cubyz/shaders/item_texture_post.fs

@@ -9,7 +9,6 @@ uniform bool transparent;
 void main() {
 	fragColor = texture(color, texCoords);
 	if(transparent) {
-		fragColor.rgb /= fragColor.a;
 		fragColor.a = 1;
 		// TODO: Remove the background color. Somehow?
 	}

src/graphics.zig

@@ -1701,7 +1701,13 @@ const block_texture = struct {
 		depthTexture = Texture.init();
 		depthTexture.bind();
 		var data: [128*128]f32 = undefined;
-		@memset(&data, main.renderer.zNear/132.0);
+
+		const z: f32 = 134;
+		const near = main.renderer.zNear;
+		const far = main.renderer.zFar;
+		const depth = ((far + near)/(near - far)*z + 2*near*far/(near - far))/-z*0.5 + 0.5;
+
+		@memset(&data, depth);
 		c.glTexImage2D(c.GL_TEXTURE_2D, 0, c.GL_R32F, textureSize, textureSize, 0, c.GL_RED, c.GL_FLOAT, &data);
 		c.glTexParameteri(c.GL_TEXTURE_2D, c.GL_TEXTURE_MIN_FILTER, c.GL_NEAREST);
 		c.glTexParameteri(c.GL_TEXTURE_2D, c.GL_TEXTURE_MAG_FILTER, c.GL_NEAREST);
@@ -1745,8 +1751,8 @@ pub fn generateBlockTexture(blockType: u16) !Texture {
 	main.game.camera.viewMatrix = Mat4f.rotationX(std.math.pi/4.0).mul(Mat4f.rotationY(-std.math.pi/4.0));
 	defer main.game.camera.viewMatrix = oldViewMatrix;
 	if(block.transparent()) {
-		c.glBlendEquationSeparate(c.GL_FUNC_ADD, c.GL_FUNC_ADD);
-		c.glBlendFuncSeparate(c.GL_DST_ALPHA, c.GL_SRC1_COLOR, c.GL_DST_ALPHA, c.GL_ZERO);
+		c.glBlendEquation(c.GL_FUNC_ADD);
+		c.glBlendFunc(c.GL_ONE, c.GL_SRC1_COLOR);
 		main.chunk.meshing.bindTransparentShaderAndUniforms(projMatrix, .{1, 1, 1}, 0);
 	} else {
 		main.chunk.meshing.bindShaderAndUniforms(projMatrix, .{1, 1, 1}, 0);

src/renderer.zig

@@ -58,7 +58,7 @@ pub fn init() !void {
 	deferredRenderPassShader = try Shader.initAndGetUniforms("assets/cubyz/shaders/deferred_render_pass.vs", "assets/cubyz/shaders/deferred_render_pass.fs", &deferredUniforms);
 	fakeReflectionShader = try Shader.initAndGetUniforms("assets/cubyz/shaders/fake_reflection.vs", "assets/cubyz/shaders/fake_reflection.fs", &fakeReflectionUniforms);
 	worldFrameBuffer.init(true, c.GL_NEAREST, c.GL_CLAMP_TO_EDGE);
-	worldFrameBuffer.updateSize(Window.width, Window.height, c.GL_RGBA16F);
+	worldFrameBuffer.updateSize(Window.width, Window.height, c.GL_RGB16F);
 	try Bloom.init();
 	try MeshSelection.init();
 	try MenuBackGround.init();
@@ -109,7 +109,7 @@ pub fn updateViewport(width: u31, height: u31, fov: f32) void {
 	lastFov = fov;
 	c.glViewport(0, 0, width, height);
 	game.projectionMatrix = Mat4f.perspective(std.math.degreesToRadians(f32, fov), @as(f32, @floatFromInt(width))/@as(f32, @floatFromInt(height)), zNear, zFar);
-	worldFrameBuffer.updateSize(width, height, c.GL_RGBA16F);
+	worldFrameBuffer.updateSize(width, height, c.GL_RGB16F);
 	worldFrameBuffer.unbind();
 }
 
@@ -227,8 +227,8 @@ pub fn renderWorld(world: *World, ambientLight: Vec3f, skyColor: Vec3f, playerPo
 	c.glTextureBarrier();
 	chunk.meshing.bindTransparentShaderAndUniforms(game.projectionMatrix, ambientLight, time);
 
-	c.glBlendEquationSeparate(c.GL_FUNC_ADD, c.GL_FUNC_ADD);
-	c.glBlendFuncSeparate(c.GL_DST_ALPHA, c.GL_SRC1_COLOR, c.GL_DST_ALPHA, c.GL_ZERO);
+	c.glBlendEquation(c.GL_FUNC_ADD);
+	c.glBlendFunc(c.GL_ONE, c.GL_SRC1_COLOR);
 	c.glDepthFunc(c.GL_LEQUAL);
 	c.glDepthMask(c.GL_FALSE);
 	{