PixelGuys · Wunka · Sep 9, 2026 · Sep 9, 2026 · Sep 9, 2026 · Sep 9, 2026
diff --git a/assets/cubyz/shaders/bloom/color_extractor_downsample.vert b/assets/cubyz/shaders/bloom/color_extractor_downsample.vert
@@ -12,7 +12,7 @@ layout(location = 0) uniform mat4 invViewMatrix;
 layout(location = 1) uniform vec2 tanXY;
 
 void main() {
-	vec2 position = inTexCoords*2 - vec2(1, 1);
+	vec2 position = inTexCoords*2+vec2(-1, -1);
 	direction = (invViewMatrix * vec4(position.x*tanXY.x, 1, position.y*tanXY.y, 0)).xyz;
 	normalizedTexCoords = inTexCoords;
 	texCoords = inTexCoords*textureSize(color, 0) - 0.25;

diff --git a/assets/cubyz/shaders/bloom/first_pass.vert b/assets/cubyz/shaders/bloom/first_pass.vert
@@ -5,6 +5,10 @@ layout(location = 0) in vec2 inTexCoords;
 layout(location = 0) out vec2 texCoords;
 
 void main() {
+#ifdef OPEN_GL
+	texCoords = vec2(inTexCoords.x, 1 - inTexCoords.y);
+#else
 	texCoords = inTexCoords;
-	gl_Position = vec4(inTexCoords*2 - vec2(1, 1), 0, 1);
+#endif
+	gl_Position = vec4(inTexCoords*2 + vec2(-1, -1), 0, 1);
 }
diff --git a/assets/cubyz/shaders/deferred_render_pass.vert b/assets/cubyz/shaders/deferred_render_pass.vert
@@ -13,7 +13,10 @@ void main() {
 	directions[1] = (invViewMatrix * vec4(1*tanXY.x, 1, -1*tanXY.y, 0)).xyz;
 	directions[2] = (invViewMatrix * vec4(-1*tanXY.x, 1, 1*tanXY.y, 0)).xyz;
 	directions[3] = (invViewMatrix * vec4(-1*tanXY.x, 1, -1*tanXY.y, 0)).xyz;
+#ifdef OPEN_GL
+	texCoords = vec2(inTexCoords.x, 1 - inTexCoords.y);
+#else
 	texCoords = inTexCoords;
-	vec2 position = inTexCoords*2 - vec2(1, 1);
-	gl_Position = vec4(position, 0, 1);
+#endif
+	gl_Position = vec4(inTexCoords*2 + vec2(-1, -1), 0, 1);
 }
diff --git a/assets/cubyz/shaders/fake_reflection.vert b/assets/cubyz/shaders/fake_reflection.vert
@@ -7,6 +7,11 @@ layout(location = 0) out vec3 coords;
 layout(location = 0) uniform float reflectionMapSize;
 
 void main() {
-	coords = vec3((inTexCoords*2 - vec2(1, 1))*(reflectionMapSize + 1)/reflectionMapSize, 1);
-	gl_Position = vec4(inTexCoords*2 - vec2(1, 1), 0, 1);
+#ifdef OPEN_GL
+	vec2 texCoords = vec2(inTexCoords.x, 1 - inTexCoords.y);
+	coords = vec3((texCoords*2 + vec2(-1, -1))*(reflectionMapSize + 1)/reflectionMapSize, 1);
+#else
+	coords = vec3((inTexCoords*2 + vec2(-1, -1))*(reflectionMapSize + 1)/reflectionMapSize, 1);
+#endif
+	gl_Position = vec4(inTexCoords*2 + vec2(-1, -1), 0, 1);
 }
diff --git a/assets/cubyz/shaders/graphics/Image.vert b/assets/cubyz/shaders/graphics/Image.vert
@@ -26,10 +26,9 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + vec2(vertex_pos.x*size.x, size.y - vertex_pos.y*size.y))/screen;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2+vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 

diff --git a/assets/cubyz/shaders/graphics/Line.vert b/assets/cubyz/shaders/graphics/Line.vert
@@ -21,10 +21,9 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + vertex_pos*direction)/screen;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2+vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 

diff --git a/assets/cubyz/shaders/graphics/Rect.vert b/assets/cubyz/shaders/graphics/Rect.vert
@@ -21,10 +21,9 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + vertex_pos*size)/screen;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2+vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 

diff --git a/assets/cubyz/shaders/graphics/RectBorder.vert b/assets/cubyz/shaders/graphics/RectBorder.vert
@@ -23,10 +23,9 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + vertex_pos.xy*size + vertex_pos.zw*lineWidth)/screen;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2+vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 

diff --git a/assets/cubyz/shaders/graphics/Text.vert b/assets/cubyz/shaders/graphics/Text.vert
@@ -25,10 +25,9 @@ void main() {
 		vertex_pos.x += vertex_pos.y/textureRect.z;
 	}
 
-	// convert glyph coords to opengl coords
 	vec4 rect = vec4(position_percentage, size_percentage);
 
-	vec2 position = vec2(rect.x+vertex_pos.x*rect.z, -rect.y+vertex_pos.y*rect.w)*2+vec2(-1, 1);
+	vec2 position = vec2(rect.x+vertex_pos.x*rect.z, rect.y-vertex_pos.y*rect.w)*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 	frag_face_pos = face_pos;

diff --git a/assets/cubyz/shaders/graphics/graph.vert b/assets/cubyz/shaders/graphics/graph.vert
@@ -27,10 +27,9 @@ layout(std430, binding = 5) buffer _data
 void main() {
 	float x = gl_VertexIndex;
 	float y = -data[(gl_VertexIndex + offset)%points];
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + dimension*vec2(x/points, y))/screen;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2 + vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 }
diff --git a/assets/cubyz/shaders/item_texture_post.vert b/assets/cubyz/shaders/item_texture_post.vert
@@ -5,6 +5,12 @@ layout(location = 0) in vec2 inTexCoords;
 layout(location = 0) out vec2 texCoords;
 
 void main() {
+
+#ifdef OPEN_GL
+	texCoords = vec2(inTexCoords.x, 1 - inTexCoords.y);
+#else
 	texCoords = inTexCoords;
-	gl_Position = vec4(inTexCoords*2 - vec2(1, 1), 0, 1);
+#endif
+
+	gl_Position = vec4(inTexCoords*2 + vec2(-1, -1), 0, 1);
 }
diff --git a/assets/cubyz/shaders/ui/button.frag b/assets/cubyz/shaders/ui/button.frag
@@ -1,5 +1,9 @@
 #version 460
 
+#ifdef OPEN_GL
+layout(origin_upper_left) in vec4 gl_FragCoord;
+#endif
+
 layout(location = 0) out vec4 frag_color;
 
 layout(location = 0) in vec2 startCoord;
@@ -20,6 +24,7 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	frag_color = texture(image, (gl_FragCoord.xy - startCoord)/(2*scale)/textureSize(image, 0));
+	vec2 textureCoords = (gl_FragCoord.xy - startCoord)/(2*scale)/textureSize(image, 0);
+	frag_color = texture(image, vec2(textureCoords.x, -textureCoords.y));
 	frag_color *= fColor;
 }
diff --git a/assets/cubyz/shaders/ui/button.vert b/assets/cubyz/shaders/ui/button.vert
@@ -23,12 +23,10 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + vertex_pos*size)/screen;
-	startCoord.x = start.x;
-	startCoord.y = screen.y - start.y;
+	startCoord = start;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2+vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 

diff --git a/assets/cubyz/shaders/ui/window_border.vert b/assets/cubyz/shaders/ui/window_border.vert
@@ -25,14 +25,13 @@ layout(push_constant, std430) uniform _ {
 #endif
 
 void main() {
-	// Convert to opengl coordinates:
 	vec2 position_percentage = (start + vertex_pos*size)/screen;
 	startCoord.x = start.x;
 	startCoord.y = screen.y - start.y - size.y;
 	endCoord.x = start.x + size.x;
 	endCoord.y = screen.y - start.y;
 
-	vec2 position = vec2(position_percentage.x, -position_percentage.y)*2+vec2(-1, 1);
+	vec2 position = position_percentage*2+vec2(-1, -1);
 
 	gl_Position = vec4(position, 0, 1);
 

diff --git a/src/graphics.zig b/src/graphics.zig
@@ -81,7 +81,7 @@ pub const draw = struct { // MARK: draw
 		c.glGetIntegerv(c.GL_VIEWPORT, &viewport);
 		var newClip = Vec4i{
 			std.math.lossyCast(i32, translation[0]),
-			viewport[3] - std.math.lossyCast(i32, translation[1] + clipRect[1]*scale),
+			std.math.lossyCast(i32, translation[1]),
 			std.math.lossyCast(i32, clipRect[0]*scale),
 			std.math.lossyCast(i32, clipRect[1]*scale),
 		};

diff --git a/src/graphics/Window.zig b/src/graphics/Window.zig
@@ -779,6 +779,7 @@ pub fn init() void { // MARK: init()
 	if (c.gladLoadGL(c.glfwGetProcAddress) == 0) {
 		@panic("Failed to load OpenGL functions from GLAD");
 	}
+	c.glClipControl(c.GL_UPPER_LEFT, c.GL_NEGATIVE_ONE_TO_ONE);
 	reloadSettings();
 
 	c.glEnable(c.GL_DEBUG_OUTPUT);

diff --git a/src/graphics/pipelines.zig b/src/graphics/pipelines.zig
@@ -820,7 +820,11 @@ pub const Pipeline = struct { // MARK: Pipeline
 		self.shader.bind();
 		if (scissor) |s| {
 			c.glEnable(c.GL_SCISSOR_TEST);
-			c.glScissor(s.offset.x, s.offset.y, @intCast(s.extent.width), @intCast(s.extent.height));
+			var viewport: [4]c_int = undefined;
+			c.glGetIntegerv(c.GL_VIEWPORT, &viewport);
+			const width: c_int = @intCast(s.extent.width);
+			const height: c_int = @intCast(s.extent.height);
+			c.glScissor(s.offset.x, viewport[1] + viewport[3] - (s.offset.y + height), width, height);
 		} else {
 			c.glDisable(c.GL_SCISSOR_TEST);
 		}
@@ -845,8 +849,8 @@ pub const Pipeline = struct { // MARK: Pipeline
 			c.glDisable(c.GL_CULL_FACE);
 		}
 		c.glFrontFace(switch (self.rasterState.frontFace) {
-			.counterClockwise => c.GL_CCW,
-			.clockwise => c.GL_CW,
+			.counterClockwise => c.GL_CW,
+			.clockwise => c.GL_CCW,
 		});
 		if (self.rasterState.depthBias) |depthBias| {
 			c.glEnable(c.GL_POLYGON_OFFSET_FILL);

diff --git a/src/renderer.zig b/src/renderer.zig
@@ -324,7 +324,7 @@ pub fn renderWorld(world: *World, ambientLight: Vec3f, skyColor: Vec3f, playerPo
 	c.glUniformMatrix4fv(deferredUniforms.invViewMatrix, 1, c.GL_TRUE, @ptrCast(&game.camera.viewMatrix.transpose()));
 	c.glUniform1f(deferredUniforms.zNear, zNear);
 	c.glUniform1f(deferredUniforms.zFar, zFar);
-	c.glUniform2f(deferredUniforms.tanXY, 1.0/game.projectionMatrix.rows[0][0], 1.0/game.projectionMatrix.rows[1][2]);
+	c.glUniform2f(deferredUniforms.tanXY, 1.0/game.projectionMatrix.rows[0][0], -1.0/game.projectionMatrix.rows[1][2]);
 
 	c.glBindFramebuffer(c.GL_FRAMEBUFFER, activeFrameBuffer);
 

diff --git a/src/systems/modelRenderer.zig b/src/systems/modelRenderer.zig
@@ -94,7 +94,7 @@ pub const client = struct { // MARK: client
 			const projectedPos = Mat4f.fromGl(main.graphics.frame_uniforms.frameData().projectionMatrix).mulVec(rotatedPos);
 			if (projectedPos[2] < 0) continue;
 			const xCenter = (1 + projectedPos[0]/projectedPos[3])*@as(f32, @floatFromInt(main.Window.width/2));
-			const yCenter = (1 - projectedPos[1]/projectedPos[3])*@as(f32, @floatFromInt(main.Window.height/2));
+			const yCenter = (1 + projectedPos[1]/projectedPos[3])*@as(f32, @floatFromInt(main.Window.height/2));
 
 			const transparency = 38.0*std.math.log10(vec.lengthSquare(pos3d) + 1) - 80.0;
 			const alpha: u32 = @trunc(std.math.clamp(0xff - transparency, 0, 0xff));

diff --git a/src/vec.zig b/src/vec.zig
@@ -302,8 +302,8 @@ pub const Mat4f = struct { // MARK: Mat4f
 		return Mat4f{
 			.rows = [4]Vec4f{
 				Vec4f{1/tanX, 0,                          0,      0},
-				Vec4f{0,      0,                          1/tanY, 0},
-				Vec4f{0,      -(far + near)/(near - far), 0,      2*near*far/(near - far)},
+				Vec4f{0,      0,                          -1/tanY, 0},
+				Vec4f{0,      (far + near)/(far - near), 0,      2*near*far/(near - far)},
 				Vec4f{0,      1,                          0,      0},
 			},
 		};