[rlsw] Fix axis aligned quad detection (#5314)

* fix `sw_quad_is_axis_aligned`

* align fix

* remove swGetColorBuffer and tweak DRM

* review alignment

Author: Bigfoot71

src/external/rlsw.h

@@ -531,7 +531,6 @@ SWAPI void swClose(void);
 SWAPI bool swResizeFramebuffer(int w, int h);
 SWAPI void swCopyFramebuffer(int x, int y, int w, int h, SWformat format, SWtype type, void *pixels);
 SWAPI void swBlitFramebuffer(int xDst, int yDst, int wDst, int hDst, int xSrc, int ySrc, int wSrc, int hSrc, SWformat format, SWtype type, void *pixels);
-SWAPI void *swGetColorBuffer(int *w, int *h);
 
 SWAPI void swEnable(SWstate state);
 SWAPI void swDisable(SWstate state);
@@ -616,12 +615,23 @@ SWAPI void swBindTexture(uint32_t id);
 #include <math.h>           // Required for: floorf(), fabsf()
 
 #if defined(_MSC_VER)
-    #define ALIGNAS(x) __declspec(align(x))
+    #define SW_ALIGN(x) __declspec(align(x))
 #elif defined(__GNUC__) || defined(__clang__)
-    #define ALIGNAS(x) __attribute__((aligned(x)))
+    #define SW_ALIGN(x) __attribute__((aligned(x)))
 #else
-    #include <stdalign.h>
-    #define ALIGNAS(x) alignas(x)
+    #define SW_ALIGN(x) // Do nothing if not available
+#endif
+
+#if defined(_M_X64) || defined(__x86_64__)
+    #define SW_ARCH_X86_64
+#elif defined(_M_IX86) || defined(__i386__)
+    #define SW_ARCH_X86
+#elif defined(_M_ARM) || defined(__arm__)
+    #define SW_ARCH_ARM32
+#elif defined(_M_ARM64) || defined(__aarch64__)
+    #define SW_ARCH_ARM64
+#elif defined(__riscv)
+    #define SW_ARCH_RISCV
 #endif
 
 #if defined(__FMA__) && defined(__AVX2__)
@@ -696,8 +706,15 @@ SWAPI void swBindTexture(uint32_t id);
 #define SW_DEG2RAD  (SW_PI/180.0f)
 #define SW_RAD2DEG  (180.0f/SW_PI)
 
-#define SW_COLOR_PIXEL_SIZE     4  //(SW_COLOR_BUFFER_BITS >> 3)
+#define SW_COLOR_PIXEL_SIZE     (SW_COLOR_BUFFER_BITS >> 3)
 #define SW_DEPTH_PIXEL_SIZE     (SW_DEPTH_BUFFER_BITS >> 3)
+#define SW_PIXEL_SIZE           (SW_COLOR_PIXEL_SIZE + SW_DEPTH_PIXEL_SIZE)
+
+#if (SW_PIXEL_SIZE <= 4)
+    #define SW_PIXEL_ALIGNMENT 4
+#else // if (SW_PIXEL_SIZE <= 8)
+    #define SW_PIXEL_ALIGNMENT 8
+#endif
 
 #if (SW_COLOR_BUFFER_BITS == 8)
     #define SW_COLOR_TYPE uint8_t
@@ -827,10 +844,12 @@ typedef struct {
 } sw_texture_t;
 
 // Pixel data type
-// WARNING: ALIGNAS() macro requires a constant value (not operand)
-typedef ALIGNAS(SW_COLOR_PIXEL_SIZE) struct {
+typedef SW_ALIGN(SW_PIXEL_ALIGNMENT) struct {
     SW_COLOR_TYPE color[SW_COLOR_PACK_COMP];
     SW_DEPTH_TYPE depth[SW_DEPTH_PACK_COMP];
+#if (SW_PIXEL_SIZE % SW_PIXEL_ALIGNMENT != 0)
+    uint8_t padding[SW_PIXEL_ALIGNMENT - SW_PIXEL_SIZE % SW_PIXEL_ALIGNMENT];
+#endif
 } sw_pixel_t;
 
 typedef struct {
@@ -2624,25 +2643,38 @@ static inline void sw_quad_clip_and_project(void)
 
 static inline bool sw_quad_is_axis_aligned(void)
 {
-    int horizontal = 0;
-    int vertical = 0;
-
+    // Reject quads with perspective projection
+    // The fast path assumes affine (non-perspective) quads,
+    // so we require all vertices to have homogeneous w = 1.0
     for (int i = 0; i < 4; i++)
     {
         if (RLSW.vertexBuffer[i].homogeneous[3] != 1.0f) return false;
-
-        const float *v0 = RLSW.vertexBuffer[i].position;
-        const float *v1 = RLSW.vertexBuffer[(i + 1)%4].position;
-
-        float dx = v1[0] - v0[0];
-        float dy = v1[1] - v0[1];
-
-        if ((fabsf(dx) > 1e-6f) && (fabsf(dy) < 1e-6f)) horizontal++;
-        else if ((fabsf(dy) > 1e-6f) && (fabsf(dx) < 1e-6f)) vertical++;
-        else return false; // Diagonal edge -> not axis-aligned
     }
 
-    return ((horizontal == 2) && (vertical == 2));
+    // Epsilon tolerance in screen space (pixels)
+    const float epsilon = 0.5f;
+
+    // Fetch screen-space positions for the four quad vertices
+    const float *p0 = RLSW.vertexBuffer[0].screen;
+    const float *p1 = RLSW.vertexBuffer[1].screen;
+    const float *p2 = RLSW.vertexBuffer[2].screen;
+    const float *p3 = RLSW.vertexBuffer[3].screen;
+
+    // Compute edge vectors between consecutive vertices
+    // These define the four sides of the quad in screen space
+    float dx01 = p1[0] - p0[0], dy01 = p1[1] - p0[1];
+    float dx12 = p2[0] - p1[0], dy12 = p2[1] - p1[1];
+    float dx23 = p3[0] - p2[0], dy23 = p3[1] - p2[1];
+    float dx30 = p0[0] - p3[0], dy30 = p0[1] - p3[1];
+
+    // Each edge must be either horizontal or vertical within epsilon tolerance
+    // If any edge deviates significantly from either axis, the quad is not axis-aligned
+    if (!((fabsf(dy01) < epsilon) || (fabsf(dx01) < epsilon))) return false;
+    if (!((fabsf(dy12) < epsilon) || (fabsf(dx12) < epsilon))) return false;
+    if (!((fabsf(dy23) < epsilon) || (fabsf(dx23) < epsilon))) return false;
+    if (!((fabsf(dy30) < epsilon) || (fabsf(dx30) < epsilon))) return false;
+
+    return true;
 }
 
 static inline void sw_quad_sort_cw(const sw_vertex_t* *output)
@@ -3660,11 +3692,6 @@ void swBlitFramebuffer(int xDst, int yDst, int wDst, int hDst, int xSrc, int ySr
 {
     sw_pixelformat_t pFormat = (sw_pixelformat_t)sw_get_pixel_format(format, type);
 
-    if (xDst == xSrc && yDst == ySrc && wDst == wSrc && hDst == hSrc)
-    {
-        swCopyFramebuffer(xSrc, ySrc, wSrc, hSrc, format, type, pixels);
-    }
-
     if (wSrc <= 0) { RLSW.errCode = SW_INVALID_VALUE; return; }
     if (hSrc <= 0) { RLSW.errCode = SW_INVALID_VALUE; return; }
 
@@ -3674,6 +3701,13 @@ void swBlitFramebuffer(int xDst, int yDst, int wDst, int hDst, int xSrc, int ySr
     xSrc = sw_clampi(xSrc, 0, wSrc);
     ySrc = sw_clampi(ySrc, 0, hSrc);
 
+    // Check if the sizes are identical after clamping the source to avoid unexpected issues
+    // REVIEW: This repeats the operations if true, so we could make a copy function without these checks
+    if (xDst == xSrc && yDst == ySrc && wDst == wSrc && hDst == hSrc)
+    {
+        swCopyFramebuffer(xSrc, ySrc, wSrc, hSrc, format, type, pixels);
+    }
+
     switch (pFormat)
     {
         case SW_PIXELFORMAT_UNCOMPRESSED_GRAYSCALE: sw_framebuffer_blit_to_GRAYALPHA(xDst, yDst, wDst, hDst, xSrc, ySrc, wSrc, hSrc, (uint8_t *)pixels); break;
@@ -3696,14 +3730,6 @@ void swBlitFramebuffer(int xDst, int yDst, int wDst, int hDst, int xSrc, int ySr
     }
 }
 
-void *swGetColorBuffer(int *w, int *h)
-{
-    if (w) *w = RLSW.framebuffer.width;
-    if (h) *h = RLSW.framebuffer.height;
-
-    return (void *)RLSW.framebuffer.pixels->color;
-}
-
 void swEnable(SWstate state)
 {
     switch (state)

src/platforms/rcore_drm.c

@@ -824,15 +824,6 @@ void SwapScreenBuffer(void)
         return;
     }
 
-    // Get the software rendered color buffer
-    int bufferWidth = 0, bufferHeight = 0;
-    void *colorBuffer = swGetColorBuffer(&bufferWidth, &bufferHeight);
-    if (!colorBuffer)
-    {
-        TRACELOG(LOG_ERROR, "DISPLAY: Failed to get software color buffer");
-        return;
-    }
-
     // Retrieving the dimensions of the display mode used
     drmModeModeInfo *mode = &platform.connector->modes[platform.modeIndex];
     uint32_t width = mode->hdisplay;
@@ -900,16 +891,8 @@ void SwapScreenBuffer(void)
     }
 
     // Copy the software rendered buffer to the dumb buffer with scaling if needed
-    if (bufferWidth == width && bufferHeight == height)
-    {
-        // Direct copy if sizes match
-        swCopyFramebuffer(0, 0, bufferWidth, bufferHeight, SW_RGBA, SW_UNSIGNED_BYTE, dumbBuffer);
-    }
-    else
-    {
-        // Scale the software buffer to match the display mode
-        swBlitFramebuffer(0, 0, width, height, 0, 0, bufferWidth, bufferHeight, SW_RGBA, SW_UNSIGNED_BYTE, dumbBuffer);
-    }
+    // NOTE: RLSW will make a simple copy if the dimensions match
+    swBlitFramebuffer(0, 0, width, height, 0, 0, width, height, SW_RGBA, SW_UNSIGNED_BYTE, dumbBuffer);
 
     // Unmap the buffer
     munmap(dumbBuffer, creq.size);