From 916210f1bfc781147b3c4ddebc74d0d69d29f438 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 29 Apr 2021 11:38:18 -0400
Subject: [PATCH] Use the same logical scaling for OpenGL that SDL2's Render
API uses.
---
src/SDL12_compat.c | 35 +++++++++++++++++++++++++----------
src/SDL20_syms.h | 2 ++
2 files changed, 27 insertions(+), 10 deletions(-)
diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 09f9fb2..2562bf9 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -4424,22 +4424,37 @@ SDL_GL_SwapBuffers(void)
if (OpenGLLogicalScalingFBO != 0) {
const GLboolean has_scissor = OpenGLFuncs.glIsEnabled(GL_SCISSOR_TEST);
GLfloat clearcolor[4];
- int scaledh, scaledw;
- int centeredx, centeredy;
+ float want_aspect, real_aspect;
int drawablew, drawableh;
+ SDL_Rect dstrect;
SDL20_GL_GetDrawableSize(VideoWindow20, &drawablew, &drawableh);
OpenGLFuncs.glGetFloatv(GL_COLOR_CLEAR_VALUE, clearcolor);
- if (drawablew < drawableh) {
- scaledw = drawablew;
- scaledh = (int) (((((double)OpenGLLogicalScalingHeight) / ((double)OpenGLLogicalScalingWidth))) * ((double)drawablew));
+ want_aspect = ((float) OpenGLLogicalScalingWidth) / ((float) OpenGLLogicalScalingHeight);
+ real_aspect = ((float) drawablew) / ((float) drawableh);
+
+ if (SDL20_fabsf(want_aspect-real_aspect) < 0.0001f) {
+ /* The aspect ratios are the same, just scale appropriately */
+ dstrect.x = 0;
+ dstrect.y = 0;
+ dstrect.w = drawablew;
+ dstrect.h = drawableh;
+ } else if (want_aspect > real_aspect) {
+ /* We want a wider aspect ratio than is available - letterbox it */
+ const float scale = ((float) drawablew) / OpenGLLogicalScalingWidth;
+ dstrect.x = 0;
+ dstrect.w = drawablew;
+ dstrect.h = (int)SDL20_floorf(OpenGLLogicalScalingHeight * scale);
+ dstrect.y = (drawableh - dstrect.h) / 2;
} else {
- scaledh = drawableh;
- scaledw = (int) (((((double)OpenGLLogicalScalingWidth) / ((double)OpenGLLogicalScalingHeight))) * ((double)drawableh));
+ /* We want a narrower aspect ratio than is available - use side-bars */
+ const float scale = ((float)drawableh) / OpenGLLogicalScalingHeight;
+ dstrect.y = 0;
+ dstrect.h = drawableh;
+ dstrect.w = (int)SDL20_floorf(OpenGLLogicalScalingWidth * scale);
+ dstrect.x = (drawablew - dstrect.w) / 2;
}
- centeredx = (drawablew - scaledw) / 2;
- centeredy = (drawableh - scaledh) / 2;
OpenGLFuncs.glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
OpenGLFuncs.glBindFramebuffer(GL_READ_FRAMEBUFFER, OpenGLLogicalScalingFBO);
@@ -4449,7 +4464,7 @@ SDL_GL_SwapBuffers(void)
OpenGLFuncs.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
OpenGLFuncs.glClear(GL_COLOR_BUFFER_BIT);
OpenGLFuncs.glBlitFramebuffer(0, 0, OpenGLLogicalScalingWidth, OpenGLLogicalScalingHeight,
- centeredx, centeredy, centeredx + scaledw, centeredy + scaledh,
+ dstrect.x, dstrect.y, dstrect.x + dstrect.w, dstrect.y + dstrect.h,
GL_COLOR_BUFFER_BIT, GL_LINEAR);
OpenGLFuncs.glBindFramebuffer(GL_FRAMEBUFFER, 0);
SDL20_GL_SwapWindow(VideoWindow20);
diff --git a/src/SDL20_syms.h b/src/SDL20_syms.h
index 5380446..b05ea70 100644
--- a/src/SDL20_syms.h
+++ b/src/SDL20_syms.h
@@ -275,6 +275,8 @@ SDL20_SYM_PASSTHROUGH(size_t,iconv,(SDL_iconv_t a, const char **b, size_t *c, ch
SDL20_SYM_PASSTHROUGH(char *,iconv_string,(const char *a, const char *b, const char *c, size_t d),(a,b,c,d),return)
SDL20_SYM(int,setenv,(const char *a, const char *b, int c),(a,b,c),return)
SDL20_SYM(int,atoi,(const char *a),(a),return)
+SDL20_SYM(float,fabsf,(float a),(a),return)
+SDL20_SYM(float,floorf,(float a),(a),return)
SDL20_SYM(SDL_Renderer *,CreateRenderer,(SDL_Window *a, int b, Uint32 c),(a,b,c),return)
SDL20_SYM(int,GetRendererInfo,(SDL_Renderer *a, SDL_RendererInfo *b),(a,b),return)