slanted-gouraud.c

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/*
 
MIT License
 
Copyright (c) 2026 PCSX-Redux authors
 
Permission is hereby granted, free of charge, to any person obtaining a copy
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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*/
 
// Slanted gouraud color suite. Every triangle here has BOTH the long
// left edge and the top edge off-axis, so the per-row left-edge color
// seed lands at a fractional x and the horizontal span delta both carry
// truncated accumulators. That compounding is precisely what the
// axis-aligned phase-7 gouraud suite cannot reach, and where a soft
// renderer can drift by a single LSB on slanted gouraud fills.
//
// All probes target interior pixels or a covered (left) vertex; none
// hit a top-left-excluded bottom/right vertex (those read sentinel).
// SG_AB reproduces the exact triangle the 24 carried-over silicon
// pixels were captured from, using full 8-bit 0xFF command colors (see
// raster-expected-phase22.h).
 
// clang-format off
 
CESTER_BODY(
 
// SG_AB: the libgouraud cross-check triangle. Raw 0xFF command colors to
// match the captured silicon. v0=(20,20)R v1=(200,60)G v2=(90,230)B.
static void drawSGAB(void) {
    rasterReset();
    rasterClearTestRegion(0, 0, 64, 32);
    rasterGouraudTri(0x0000ffu, 20,  20,
                     0x00ff00u, 200, 60,
                     0xff0000u, 90,  230);
    rasterFlushPrimitive();
}
 
// SG1: medium slanted RGB triangle, suite idiom (5-bit colors).
static void drawSG1(void) {
    rasterReset();
    rasterClearTestRegion(0, 0, 64, 56);
    rasterGouraudTri(RASTER_CMD_RED,   8,  4,
                     RASTER_CMD_GREEN, 58, 22,
                     RASTER_CMD_BLUE,  22, 52);
    rasterFlushPrimitive();
}
 
// SG2: flatter slanted RGB triangle, apex-low orientation.
static void drawSG2(void) {
    rasterReset();
    rasterClearTestRegion(0, 0, 72, 56);
    rasterGouraudTri(RASTER_CMD_RED,   40, 6,
                     RASTER_CMD_GREEN, 70, 48,
                     RASTER_CMD_BLUE,  6,  40);
    rasterFlushPrimitive();
}
 
// SG_R: R-only slanted gradient. Apex R=31, base verts R=0. Isolates a
// single channel's accumulator on a slanted shape.
static void drawSGR(void) {
    rasterReset();
    rasterClearTestRegion(0, 0, 56, 56);
    rasterGouraudTri(RASTER_CMD_RED, 6,  6,
                     0u,             54, 18,
                     0u,             18, 50);
    rasterFlushPrimitive();
}
 
// SG3: narrow / steep slanted triangle.
static void drawSG3(void) {
    rasterReset();
    rasterClearTestRegion(0, 0, 48, 56);
    rasterGouraudTri(RASTER_CMD_RED,   30, 4,
                     RASTER_CMD_GREEN, 40, 50,
                     RASTER_CMD_BLUE,  20, 46);
    rasterFlushPrimitive();
}
 
)  // CESTER_BODY
 
// --------------------------------------------------------------------------
// SG_AB: 24 silicon cross-check probes
// --------------------------------------------------------------------------
 
CESTER_TEST(sg_ab_26_22, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_26_22, 26, 22); )
CESTER_TEST(sg_ab_24_23, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_24_23, 24, 23); )
CESTER_TEST(sg_ab_26_23, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_26_23, 26, 23); )
CESTER_TEST(sg_ab_27_24, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_27_24, 27, 24); )
CESTER_TEST(sg_ab_30_24, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_30_24, 30, 24); )
CESTER_TEST(sg_ab_32_24, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_32_24, 32, 24); )
CESTER_TEST(sg_ab_37_24, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_37_24, 37, 24); )
CESTER_TEST(sg_ab_27_25, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_27_25, 27, 25); )
CESTER_TEST(sg_ab_32_25, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_32_25, 32, 25); )
CESTER_TEST(sg_ab_22_26, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_22_26, 22, 26); )
CESTER_TEST(sg_ab_27_26, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_27_26, 27, 26); )
CESTER_TEST(sg_ab_35_26, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_35_26, 35, 26); )
CESTER_TEST(sg_ab_25_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_25_27, 25, 27); )
CESTER_TEST(sg_ab_28_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_28_27, 28, 27); )
CESTER_TEST(sg_ab_33_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_33_27, 33, 27); )
CESTER_TEST(sg_ab_38_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_38_27, 38, 27); )
CESTER_TEST(sg_ab_41_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_41_27, 41, 27); )
CESTER_TEST(sg_ab_43_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_43_27, 43, 27); )
CESTER_TEST(sg_ab_49_27, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_49_27, 49, 27); )
CESTER_TEST(sg_ab_28_28, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_28_28, 28, 28); )
CESTER_TEST(sg_ab_29_28, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_29_28, 29, 28); )
CESTER_TEST(sg_ab_30_28, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_30_28, 30, 28); )
CESTER_TEST(sg_ab_33_28, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_33_28, 33, 28); )
CESTER_TEST(sg_ab_49_28, gpu_raster_phase22, drawSGAB(); ASSERT_PIXEL_EQ(SG_AB_49_28, 49, 28); )
 
// --------------------------------------------------------------------------
// SG1: medium slanted RGB triangle (interior probes)
// --------------------------------------------------------------------------
 
CESTER_TEST(sg1_29_26, gpu_raster_phase22, drawSG1(); ASSERT_PIXEL_EQ(SG1_29_26, 29, 26); )
CESTER_TEST(sg1_24_24, gpu_raster_phase22, drawSG1(); ASSERT_PIXEL_EQ(SG1_24_24, 24, 24); )
CESTER_TEST(sg1_36_28, gpu_raster_phase22, drawSG1(); ASSERT_PIXEL_EQ(SG1_36_28, 36, 28); )
CESTER_TEST(sg1_20_20, gpu_raster_phase22, drawSG1(); ASSERT_PIXEL_EQ(SG1_20_20, 20, 20); )
CESTER_TEST(sg1_30_32, gpu_raster_phase22, drawSG1(); ASSERT_PIXEL_EQ(SG1_30_32, 30, 32); )
CESTER_TEST(sg1_40_24, gpu_raster_phase22, drawSG1(); ASSERT_PIXEL_EQ(SG1_40_24, 40, 24); )
 
// --------------------------------------------------------------------------
// SG2: flatter slanted RGB triangle (v2 covered vertex + interior)
// --------------------------------------------------------------------------
 
CESTER_TEST(sg2_v2_6_40, gpu_raster_phase22, drawSG2(); ASSERT_PIXEL_EQ(SG2_V2_6_40, 6,  40); )
CESTER_TEST(sg2_39_31,   gpu_raster_phase22, drawSG2(); ASSERT_PIXEL_EQ(SG2_39_31,   39, 31); )
CESTER_TEST(sg2_30_30,   gpu_raster_phase22, drawSG2(); ASSERT_PIXEL_EQ(SG2_30_30,   30, 30); )
CESTER_TEST(sg2_48_32,   gpu_raster_phase22, drawSG2(); ASSERT_PIXEL_EQ(SG2_48_32,   48, 32); )
CESTER_TEST(sg2_40_20,   gpu_raster_phase22, drawSG2(); ASSERT_PIXEL_EQ(SG2_40_20,   40, 20); )
CESTER_TEST(sg2_20_34,   gpu_raster_phase22, drawSG2(); ASSERT_PIXEL_EQ(SG2_20_34,   20, 34); )
 
// --------------------------------------------------------------------------
// SG_R: R-only slanted gradient (interior probes)
// --------------------------------------------------------------------------
 
CESTER_TEST(sgr_8_8,   gpu_raster_phase22, drawSGR(); ASSERT_PIXEL_EQ(SGR_8_8,   8,  8);  )
CESTER_TEST(sgr_26_25, gpu_raster_phase22, drawSGR(); ASSERT_PIXEL_EQ(SGR_26_25, 26, 25); )
CESTER_TEST(sgr_16_16, gpu_raster_phase22, drawSGR(); ASSERT_PIXEL_EQ(SGR_16_16, 16, 16); )
CESTER_TEST(sgr_22_28, gpu_raster_phase22, drawSGR(); ASSERT_PIXEL_EQ(SGR_22_28, 22, 28); )
CESTER_TEST(sgr_31_20, gpu_raster_phase22, drawSGR(); ASSERT_PIXEL_EQ(SGR_31_20, 31, 20); )
CESTER_TEST(sgr_13_22, gpu_raster_phase22, drawSGR(); ASSERT_PIXEL_EQ(SGR_13_22, 13, 22); )
 
// --------------------------------------------------------------------------
// SG3: narrow / steep slanted triangle (v2 covered vertex + interior)
// --------------------------------------------------------------------------
 
CESTER_TEST(sg3_v2_20_46, gpu_raster_phase22, drawSG3(); ASSERT_PIXEL_EQ(SG3_V2_20_46, 20, 46); )
CESTER_TEST(sg3_30_33,    gpu_raster_phase22, drawSG3(); ASSERT_PIXEL_EQ(SG3_30_33,    30, 33); )
CESTER_TEST(sg3_30_22,    gpu_raster_phase22, drawSG3(); ASSERT_PIXEL_EQ(SG3_30_22,    30, 22); )
CESTER_TEST(sg3_31_40,    gpu_raster_phase22, drawSG3(); ASSERT_PIXEL_EQ(SG3_31_40,    31, 40); )
CESTER_TEST(sg3_28_30,    gpu_raster_phase22, drawSG3(); ASSERT_PIXEL_EQ(SG3_28_30,    28, 30); )
CESTER_TEST(sg3_33_38,    gpu_raster_phase22, drawSG3(); ASSERT_PIXEL_EQ(SG3_33_38,    33, 38); )