From a303aae4208a478aee62ef1caec58a94a201fe64 Mon Sep 17 00:00:00 2001
From: wheremyfoodat <44909372+wheremyfoodat@users.noreply.github.com>
Date: Tue, 25 Feb 2025 16:25:47 +0200
Subject: [PATCH] GL: Test a hack for emulating RTT

---
 src/core/PICA/shader_gen_glsl.cpp          |  6 +++---
 src/core/renderer_gl/renderer_gl.cpp       |  5 +++++
 src/core/renderer_gl/textures.cpp          | 22 +++++++++++-----------
 src/host_shaders/opengl_vertex_shader.vert |  6 +++---
 4 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/src/core/PICA/shader_gen_glsl.cpp b/src/core/PICA/shader_gen_glsl.cpp
index a9ad3a90..970a603d 100644
--- a/src/core/PICA/shader_gen_glsl.cpp
+++ b/src/core/PICA/shader_gen_glsl.cpp
@@ -798,9 +798,9 @@ void main() {
 	vec4 colourAbs = abs(a_vertexColour);
 	v_colour = min(colourAbs, vec4(1.f));
 
-	v_texcoord0 = vec3(a_texcoord0.x, 1.0 - a_texcoord0.y, a_texcoord0_w);
-	v_texcoord1 = vec2(a_texcoord1.x, 1.0 - a_texcoord1.y);
-	v_texcoord2 = vec2(a_texcoord2.x, 1.0 - a_texcoord2.y);
+	v_texcoord0 = vec3(a_texcoord0.x, a_texcoord0.y, a_texcoord0_w);
+	v_texcoord1 = vec2(a_texcoord1.x, a_texcoord1.y);
+	v_texcoord2 = vec2(a_texcoord2.x, a_texcoord2.y);
 	v_view = a_view;
 	v_quaternion = a_quaternion;
 
diff --git a/src/core/renderer_gl/renderer_gl.cpp b/src/core/renderer_gl/renderer_gl.cpp
index 2d54e586..10a37792 100644
--- a/src/core/renderer_gl/renderer_gl.cpp
+++ b/src/core/renderer_gl/renderer_gl.cpp
@@ -361,6 +361,11 @@ void RendererGL::bindTexturesToSlots() {
 		u32 format = regs[ioBase + (i == 0 ? 13 : 5)] & 0xF;
 
 		glActiveTexture(GL_TEXTURE0 + i);
+		auto fb = getColourBuffer(addr, static_cast<PICA::ColorFmt>(format), width, height, false);
+		if (fb.has_value()) {
+			fb->texture.bind();
+			continue;
+		}
 
 		if (addr != 0) [[likely]] {
 			Texture targetTex(addr, static_cast<PICA::TextureFmt>(format), width, height, config);
diff --git a/src/core/renderer_gl/textures.cpp b/src/core/renderer_gl/textures.cpp
index 7f4c31bf..775f0309 100644
--- a/src/core/renderer_gl/textures.cpp
+++ b/src/core/renderer_gl/textures.cpp
@@ -248,17 +248,17 @@ u32 Texture::decodeTexel(u32 u, u32 v, PICA::TextureFmt fmt, std::span<const u8>
 }
 
 void Texture::decodeTexture(std::span<const u8> data) {
-    std::vector<u32> decoded;
-    decoded.reserve(u64(size.u()) * u64(size.v()));
+	std::vector<u32> decoded;
+	decoded.reserve(u64(size.u()) * u64(size.v()));
 
-    // Decode texels line by line
-    for (u32 v = 0; v < size.v(); v++) {
-        for (u32 u = 0; u < size.u(); u++) {
-            u32 colour = decodeTexel(u, v, format, data);
-            decoded.push_back(colour);
-        }
-    }
+	// Decode texels line by line
+	for (u32 v = size.v() - 1; s32(v) >= 0; v--) {
+		for (u32 u = 0; u < size.u(); u++) {
+			u32 colour = decodeTexel(u, v, format, data);
+			decoded.push_back(colour);
+		}
+	}
 
-    texture.bind();
-    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size.u(), size.v(), GL_RGBA, GL_UNSIGNED_BYTE, decoded.data());
+	texture.bind();
+	glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size.u(), size.v(), GL_RGBA, GL_UNSIGNED_BYTE, decoded.data());
 }
diff --git a/src/host_shaders/opengl_vertex_shader.vert b/src/host_shaders/opengl_vertex_shader.vert
index 057f9a88..a6ed966a 100644
--- a/src/host_shaders/opengl_vertex_shader.vert
+++ b/src/host_shaders/opengl_vertex_shader.vert
@@ -60,9 +60,9 @@ void main() {
         v_colour = min(colourAbs, vec4(1.f));
 
 	// Flip y axis of UVs because OpenGL uses an inverted y for texture sampling compared to the PICA
-	v_texcoord0 = vec3(a_texcoord0.x, 1.0 - a_texcoord0.y, a_texcoord0_w);
-	v_texcoord1 = vec2(a_texcoord1.x, 1.0 - a_texcoord1.y);
-	v_texcoord2 = vec2(a_texcoord2.x, 1.0 - a_texcoord2.y);
+	v_texcoord0 = vec3(a_texcoord0.x, a_texcoord0.y, a_texcoord0_w);
+	v_texcoord1 = vec2(a_texcoord1.x, a_texcoord1.y);
+	v_texcoord2 = vec2(a_texcoord2.x, a_texcoord2.y);
 	v_view = a_view;
 
 	for (int i = 0; i < 6; i++) {