mirror of
https://github.com/RetroDECK/Supermodel.git
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326 lines
9.1 KiB
C
326 lines
9.1 KiB
C
/**
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** Supermodel
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** A Sega Model 3 Arcade Emulator.
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** Copyright 2011-2012 Bart Trzynadlowski, Nik Henson
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**
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** This file is part of Supermodel.
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**
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** Supermodel is free software: you can redistribute it and/or modify it under
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** the terms of the GNU General Public License as published by the Free
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** Software Foundation, either version 3 of the License, or (at your option)
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** any later version.
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**
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** Supermodel is distributed in the hope that it will be useful, but WITHOUT
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** ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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** FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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** more details.
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**
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** You should have received a copy of the GNU General Public License along
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** with Supermodel. If not, see <http://www.gnu.org/licenses/>.
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**/
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/*
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* Shaders2D.h
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*
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* Header file containing the 2D vertex and fragment shaders.
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*/
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#ifndef INCLUDED_SHADERS2D_H
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#define INCLUDED_SHADERS2D_H
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// Vertex shader
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static const char s_vertexShaderSource[] = R"glsl(
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#version 410 core
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// outputs
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out vec2 fsTexCoord;
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void main(void)
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{
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const vec4 vertices[] = vec4[](vec4(-1.0, -1.0, 0.0, 1.0),
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vec4(-1.0, 1.0, 0.0, 1.0),
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vec4( 1.0, -1.0, 0.0, 1.0),
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vec4( 1.0, 1.0, 0.0, 1.0));
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fsTexCoord = ((vertices[gl_VertexID % 4].xy + 1.0) / 2.0);
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fsTexCoord.y = 1.0 - fsTexCoord.y; // flip upside down
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gl_Position = vertices[gl_VertexID % 4];
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}
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)glsl";
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// Fragment shader
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static const char s_fragmentShaderSource[] = R"glsl(
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#version 410 core
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// inputs
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uniform sampler2D tex1; // texture
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in vec2 fsTexCoord;
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// outputs
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out vec4 fragColor;
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void main()
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{
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fragColor = texture(tex1, fsTexCoord);
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}
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)glsl";
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// Vertex shader
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static const char s_vertexShaderTileGen[] = R"glsl(
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#version 410 core
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uniform float lineStart; // defined as a % of the viewport height in the range 0-1. So 0 is top line, 0.5 is line 192 etc
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uniform float lineEnd;
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void main(void)
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{
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const float v1 = -1.0;
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const float v2 = 1.0;
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vec4 vertices[] = vec4[]( vec4(-1.0, v1, 0.0, 1.0),
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vec4(-1.0, v2, 0.0, 1.0),
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vec4( 1.0, v1, 0.0, 1.0),
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vec4( 1.0, v2, 0.0, 1.0));
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float top = ((v2 - v1) * lineStart) + v1;
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float bottom = ((v2 - v1) * lineEnd ) + v1;
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vertices[0].y = top;
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vertices[2].y = top;
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vertices[1].y = bottom;
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vertices[3].y = bottom;
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gl_Position = vertices[gl_VertexID % 4];
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}
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)glsl";
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// Fragment shader
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static const char s_fragmentShaderTileGen[] = R"glsl(
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#version 410 core
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//layout(origin_upper_left) in vec4 gl_FragCoord;
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// inputs
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uniform usampler2D vram; // texture 512x512
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uniform usampler2D palette; // texture 128x256 - actual dimensions dont matter too much but we have to stay in the limits of max tex width/height, so can't have 1 giant 1d array
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uniform uint regs[32];
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uniform int layerNumber;
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// outputs
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out vec4 fragColor;
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ivec2 GetVRamCoords(int offset)
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{
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return ivec2(offset % 512, offset / 512);
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}
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ivec2 GetPaletteCoords(int offset)
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{
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return ivec2(offset % 128, offset / 128);
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}
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uint GetLineMask(int layerNum, int yCoord)
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{
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uint shift = (layerNum<2) ? 16u : 0u; // need to check this, we could be endian swapped so could be wrong
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uint maskPolarity = ((layerNum & 1) > 0) ? 0xFFFFu : 0x0000u;
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int index = (0xF7000 / 4) + yCoord;
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ivec2 coords = GetVRamCoords(index);
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uint mask = ((texelFetch(vram,coords,0).r >> shift) & 0xFFFFu) ^ maskPolarity;
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return mask;
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}
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bool GetPixelMask(int layerNum, int xCoord, int yCoord)
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{
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uint lineMask = GetLineMask(layerNum, yCoord);
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uint maskTest = 1 << (15-(xCoord/32));
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return (lineMask & maskTest) != 0;
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}
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int GetLineScrollValue(int layerNum, int yCoord)
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{
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int index = ((0xF6000 + (layerNum * 0x400)) / 4) + (yCoord / 2);
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int shift = (1 - (yCoord % 2)) * 16;
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ivec2 coords = GetVRamCoords(index);
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return int((texelFetch(vram,coords,0).r >> shift) & 0xFFFFu);
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}
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int GetTileNumber(int xCoord, int yCoord, int xScroll, int yScroll)
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{
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int xIndex = ((xCoord + xScroll) / 8) & 0x3F;
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int yIndex = ((yCoord + yScroll) / 8) & 0x3F;
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return (yIndex*64) + xIndex;
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}
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int GetTileData(int layerNum, int tileNumber)
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{
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int addressBase = (0xF8000 + (layerNum * 0x2000)) / 4;
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int offset = tileNumber / 2; // two tiles per 32bit word
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int shift = (1 - (tileNumber % 2)) * 16; // triple check this
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ivec2 coords = GetVRamCoords(addressBase+offset);
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uint data = (texelFetch(vram,coords,0).r >> shift) & 0xFFFFu;
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return int(data);
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}
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int GetVFine(int yCoord, int yScroll)
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{
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return (yCoord + yScroll) & 7;
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}
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int GetHFine(int xCoord, int xScroll)
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{
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return (xCoord + xScroll) & 7;
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}
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// register data
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bool LineScrollMode (int layerNum) { return (regs[0x60/4 + layerNum] & 0x8000) != 0; }
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int GetHorizontalScroll(int layerNum) { return int(regs[0x60 / 4 + layerNum] &0x3FFu); }
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int GetVerticalScroll (int layerNum) { return int((regs[0x60/4 + layerNum] >> 16) & 0x1FFu); }
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int LayerPriority () { return int((regs[0x20/4] >> 8) & 0xFu); }
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bool LayerIs4Bit (int layerNum) { return (regs[0x20/4] & (1 << (12 + layerNum))) != 0; }
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bool LayerEnabled (int layerNum) { return (regs[0x60/4 + layerNum] & 0x80000000) != 0; }
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bool LayerSelected (int layerNum) { return (LayerPriority() & (1 << layerNum)) == 0; }
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float Int8ToFloat(uint c)
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{
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if((c & 0x80u) > 0u) { // this is a bit harder in GLSL. Top bit means negative number, we extend to make 32bit
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return float(int(c | 0xFFFFFF00u)) / 128.0;
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}
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else {
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return float(c) / 127.0;
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}
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}
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vec4 AddColourOffset(int layerNum, vec4 colour)
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{
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uint offsetReg = regs[(0x40/4) + layerNum/2];
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vec4 c;
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c.b = Int8ToFloat((offsetReg >>16) & 0xFFu);
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c.g = Int8ToFloat((offsetReg >> 8) & 0xFFu);
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c.r = Int8ToFloat((offsetReg >> 0) & 0xFFu);
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c.a = 0.0;
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colour += c;
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return clamp(colour,0.0,1.0); // clamp is probably not needed since will get clamped on render target
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}
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vec4 Int16ColourToVec4(uint colour)
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{
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uint alpha = (colour>>15); // top bit is alpha. 1 means clear, 0 opaque
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alpha = ~alpha; // invert
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alpha = alpha & 0x1u; // mask bit
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vec4 c;
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c.r = float((colour >> 0 ) & 0x1F) / 31.0;
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c.g = float((colour >> 5 ) & 0x1F) / 31.0;
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c.b = float((colour >> 10) & 0x1F) / 31.0;
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c.a = float(alpha) / 1.0;
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c.rgb *= c.a; // multiply by alpha value, this will push transparent to black, no branch needed
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return c;
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}
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vec4 GetColour(int layerNum, int paletteOffset)
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{
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ivec2 coords = GetPaletteCoords(paletteOffset);
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uint colour = texelFetch(palette,coords,0).r;
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vec4 col = Int16ColourToVec4(colour); // each colour is only 16bits, but occupies 32bits
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return AddColourOffset(layerNum,col); // apply colour offsets from registers
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}
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vec4 Draw4Bit(int layerNum, int tileData, int hFine, int vFine)
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{
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// Tile pattern offset: each tile occupies 32 bytes when using 4-bit pixels (offset of tile pattern within VRAM)
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int patternOffset = ((tileData & 0x3FFF) << 1) | ((tileData >> 15) & 1);
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patternOffset *= 32;
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patternOffset /= 4;
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// Upper color bits; the lower 4 bits come from the tile pattern
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int paletteIndex = tileData & 0x7FF0;
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ivec2 coords = GetVRamCoords(patternOffset+vFine);
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uint pattern = texelFetch(vram,coords,0).r;
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pattern = (pattern >> ((7-hFine)*4)) & 0xFu; // get the pattern for our horizontal value
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return GetColour(layerNum, paletteIndex | int(pattern));
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}
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vec4 Draw8Bit(int layerNum, int tileData, int hFine, int vFine)
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{
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// Tile pattern offset: each tile occupies 64 bytes when using 8-bit pixels
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int patternOffset = tileData & 0x3FFF;
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patternOffset *= 64;
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patternOffset /= 4;
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// Upper color bits
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int paletteIndex = tileData & 0x7F00;
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// each read is 4 pixels
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int offset = hFine / 4;
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ivec2 coords = GetVRamCoords(patternOffset+(vFine*2)+offset); // 8-bit pixels, each line is two words
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uint pattern = texelFetch(vram,coords,0).r;
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pattern = (pattern >> ((3-(hFine%4))*8)) & 0xFFu; // shift out the bits we want for this pixel
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return GetColour(layerNum, paletteIndex | int(pattern));
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}
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void main()
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{
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ivec2 pos = ivec2(gl_FragCoord.xy);
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int scrollX;
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if(LineScrollMode(layerNumber)) {
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scrollX = GetLineScrollValue(layerNumber, pos.y);
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}
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else {
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scrollX = GetHorizontalScroll(layerNumber);
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}
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int scrollY = GetVerticalScroll(layerNumber);
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int tileNumber = GetTileNumber(pos.x,pos.y,scrollX,scrollY);
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int hFine = GetHFine(pos.x,scrollX);
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int vFine = GetVFine(pos.y,scrollY);
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bool pixelMask = GetPixelMask(layerNumber,pos.x,pos.y);
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if(pixelMask==true) {
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int tileData = GetTileData(layerNumber,tileNumber);
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if(LayerIs4Bit(layerNumber)) {
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fragColor = Draw4Bit(layerNumber,tileData,hFine,vFine);
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}
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else {
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fragColor = Draw8Bit(layerNumber,tileData,hFine,vFine);
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}
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}
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else {
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fragColor = vec4(0.0);
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}
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}
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)glsl";
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#endif // INCLUDED_SHADERS2D_H
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