Add GLES2 2D renderer + Linux display manager

First implementation with Linux display manager.

- Add single-threaded mode for EditorResourcePreview (needed for OpenGL).

Co-authored-by: clayjohn <claynjohn@gmail.com>
Co-authored-by: Fabio Alessandrelli <fabio.alessandrelli@gmail.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/drivers/gles2/shaders/cube_to_dp.glsl b/drivers/gles2/shaders/cube_to_dp.glsl
new file mode 100644
index 0000000000..1612ec3d5a
--- /dev/null
+++ b/drivers/gles2/shaders/cube_to_dp.glsl
@@ -0,0 +1,100 @@
+/* clang-format off */
+[vertex]
+
+#ifdef USE_GLES_OVER_GL
+#define lowp
+#define mediump
+#define highp
+#else
+precision mediump float;
+precision mediump int;
+#endif
+
+attribute highp vec4 vertex_attrib; // attrib:0
+/* clang-format on */
+attribute vec2 uv_in; // attrib:4
+
+varying vec2 uv_interp;
+
+void main() {
+	uv_interp = uv_in;
+	gl_Position = vertex_attrib;
+}
+
+/* clang-format off */
+[fragment]
+
+#ifdef USE_GLES_OVER_GL
+#define lowp
+#define mediump
+#define highp
+#else
+#if defined(USE_HIGHP_PRECISION)
+precision highp float;
+precision highp int;
+#else
+precision mediump float;
+precision mediump int;
+#endif
+#endif
+
+uniform highp samplerCube source_cube; //texunit:0
+/* clang-format on */
+varying vec2 uv_interp;
+
+uniform bool z_flip;
+uniform highp float z_far;
+uniform highp float z_near;
+uniform highp float bias;
+
+void main() {
+	highp vec3 normal = vec3(uv_interp * 2.0 - 1.0, 0.0);
+	/*
+	if (z_flip) {
+		normal.z = 0.5 - 0.5 * ((normal.x * normal.x) + (normal.y * normal.y));
+	} else {
+		normal.z = -0.5 + 0.5 * ((normal.x * normal.x) + (normal.y * normal.y));
+	}
+	*/
+
+	//normal.z = sqrt(1.0 - dot(normal.xy, normal.xy));
+	//normal.xy *= 1.0 + normal.z;
+
+	normal.z = 0.5 - 0.5 * ((normal.x * normal.x) + (normal.y * normal.y));
+	normal = normalize(normal);
+	/*
+	normal.z = 0.5;
+	normal = normalize(normal);
+	*/
+
+	if (!z_flip) {
+		normal.z = -normal.z;
+	}
+
+	//normal = normalize(vec3( uv_interp * 2.0 - 1.0, 1.0 ));
+	float depth = textureCube(source_cube, normal).r;
+
+	// absolute values for direction cosines, bigger value equals closer to basis axis
+	vec3 unorm = abs(normal);
+
+	if ((unorm.x >= unorm.y) && (unorm.x >= unorm.z)) {
+		// x code
+		unorm = normal.x > 0.0 ? vec3(1.0, 0.0, 0.0) : vec3(-1.0, 0.0, 0.0);
+	} else if ((unorm.y > unorm.x) && (unorm.y >= unorm.z)) {
+		// y code
+		unorm = normal.y > 0.0 ? vec3(0.0, 1.0, 0.0) : vec3(0.0, -1.0, 0.0);
+	} else if ((unorm.z > unorm.x) && (unorm.z > unorm.y)) {
+		// z code
+		unorm = normal.z > 0.0 ? vec3(0.0, 0.0, 1.0) : vec3(0.0, 0.0, -1.0);
+	} else {
+		// oh-no we messed up code
+		// has to be
+		unorm = vec3(1.0, 0.0, 0.0);
+	}
+
+	float depth_fix = 1.0 / dot(normal, unorm);
+
+	depth = 2.0 * depth - 1.0;
+	float linear_depth = 2.0 * z_near * z_far / (z_far + z_near - depth * (z_far - z_near));
+	gl_FragDepth = (linear_depth * depth_fix + bias) / z_far;
+}